JP2008215107A - Compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To appropriately suppress the occurrence of a rotating stall in a compressor without deteriorating efficiency. <P>SOLUTION: A rotary shaft 12 is rotatably supported to a casing 11 via bearings 13, 14, and an impeller 15 for compressing fluid is mounted on the rotary shaft 12. The compressor is equipped with an accelerometer 21 for detecting axis vibration of the bearing 13, an oil cooler 29 for cooling oil supplied to the bearings 13, 14 and making it highly viscous, and a controller 25 for changing supporting rigidity of the rotary shaft 12 by the bearings 13, 14 by controlling operation of the oil cooler 29 based on the axis vibration of the bearing 13 detected by the accelerometer 21. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a compressor that pressurizes and delivers a fluid, and is applied to, for example, a centrifugal compressor and an axial flow compressor.

  As a compressor that compresses gas, for example, a centrifugal compressor is known. In a general centrifugal compressor, a rotating shaft is rotatably supported by a pair of bearings in a casing, and an impeller having a plurality of blades is mounted on the rotating shaft, and a suction passage is provided upstream of the impeller. On the other hand, a discharge passage is formed on the downstream side. Accordingly, when the rotating shaft is rotated by the motor, the impeller rotates, the fluid is sucked into the casing through the suction passage, the pressure is increased in the process of passing through the impeller, and the formed compressed fluid is discharged to the discharge passage.

  In such a centrifugal compressor, it is desirable that the fluid is stably supplied from a region where the supply amount of fluid is small to a region where it is large when viewed from the side where the compressed fluid is used. However, when this centrifugal compressor is operated with a reduced supply amount, a phenomenon called a turning stall may occur, and the shaft vibration is excited by the turning stall. This turning stall is a phenomenon in which a stalled part (high pressure part) called a turning stall cell occurs in one or more places on the entire circumference of the impeller and propagates in the rotational direction at a speed slower than the rotational speed of the impeller. Since the pressure distribution in the circumferential direction of the impeller is not uniform, a forced external force is applied to the rotating shaft, and the shaft vibration in this low frequency region becomes large. And when this turning stall occurs, the shaft vibration of the rotating shaft increases, leading to damage to the bearing and a decrease in the service life.

  Therefore, for example, there is one described in Patent Document 1 below to suppress the occurrence of a rotating stall in a compressor or the like. The blower described in this Patent Document 1 is provided with a sensor for detecting the amount of information of turning stall inside and outside the casing or in the pipe line, and the opening of the damper and the rotation speed of the blower are controlled by the output of this sensor. The operation point of the blower is controlled so as not to enter the ultra low frequency sound generation region.

Japanese Patent Laid-Open No. 58-144893

  The above-described conventional blower controls the opening degree of the damper and the rotation speed of the blower based on the information amount of the rotation stall detected by the sensor, and controls so that the operating point of the blower does not enter the ultra low frequency sound generation region. This control can suppress the occurrence of turning stall. However, with this control method, it is possible to suppress the occurrence of turning stall, but when a small flow rate is required, it is necessary to reduce the flow rate with another system, and as a whole, the efficiency of the blower itself decreases. There is a problem of end.

  The present invention solves such a problem, and an object of the present invention is to provide a compressor that can appropriately suppress the occurrence of turning stall without reducing the efficiency.

  In order to achieve the above object, the compressor of the invention of claim 1 is a compressor in which a rotating shaft is rotatably supported by a casing via a bearing, and an impeller for compressing fluid is mounted on the rotating shaft. Based on the shaft vibration detecting means for detecting the shaft vibration of the rotating shaft, the support rigidity changing means for changing the support rigidity of the rotating shaft by the bearing, and the shaft vibration of the rotating shaft detected by the shaft vibration detecting means. Control means for changing the support rigidity of the rotating shaft by the bearing by controlling the support rigidity changing means.

  In the compressor according to a second aspect of the present invention, the support rigidity changing means has a lubricating oil cooling means for cooling the lubricating oil supplied to the bearing.

  The compressor according to a third aspect of the invention is characterized in that the support rigidity changing means includes an actuator that changes a support force of the bearing with respect to the rotating shaft.

  In the compressor according to a fourth aspect of the present invention, the bearing has a plurality of bearing pads divided in the circumferential direction so as to support the rotating shaft, and the actuator has a pressing force of the bearing pad against the rotating shaft. It is characterized by changing.

  In the compressor according to claim 5, the bearing has a plurality of cylindrical bearing pads so as to support the rotating shaft, and the actuator deforms the bearing pad to deform the rotating shaft. The pressing force of the bearing pad is changed.

  In the compressor according to a sixth aspect of the present invention, the bearing is a magnetic bearing that supports the rotating shaft by an attractive force of a magnetic field, and the support rigidity changing means controls the current supplied to the magnetic bearing and repels it. It is characterized by having a magnetic bearing controller that changes the force or attractive force.

  In the compressor according to the seventh aspect of the present invention, a non-contact type sealing mechanism is provided between the casing and the rotating shaft, and the rotation direction of the rotating shaft is opposite to the seal gap in the non-contact type sealing mechanism. Fluid supply means for supplying fluid is provided, and the control means controls the support rigidity changing means based on the shaft vibration of the rotating shaft detected by the shaft vibration detection means, and also controls the fluid supply means. It is characterized by that.

  According to the compressor of the first aspect of the present invention, the shaft vibration detecting means for detecting the shaft vibration of the rotating shaft, the support rigidity changing means for changing the support rigidity of the rotating shaft by the bearing, and the rotation detected by the shaft vibration detecting means. Since the control means for changing the support rigidity of the rotating shaft by the bearing is provided by controlling the support rigidity changing means based on the shaft vibration of the shaft, when the shaft vibration detecting means detects the shaft vibration of the rotating shaft, the control means By controlling the support rigidity changing means based on the shaft vibration of the rotating shaft and changing the supporting rigidity of the rotating shaft by the bearing, the shaft vibration of the rotating shaft can be suppressed, and the rotation stall can be achieved without reducing the efficiency. Can be suppressed appropriately.

  According to the compressor of the second aspect of the present invention, since the lubricating oil cooling means for cooling the lubricating oil supplied to the bearing is provided as the support rigidity changing means, when the shaft vibration detecting means detects the shaft vibration of the rotating shaft, The oil cooling means cools the lubricating oil supplied to the bearing, thereby lowering the viscosity of the lubricating oil and increasing the support rigidity, and can appropriately suppress the shaft vibration of the rotating shaft.

  According to the compressor of the invention of claim 3, since the actuator for changing the bearing support force with respect to the rotating shaft is provided as the supporting rigidity changing means, when the shaft vibration detecting means detects the shaft vibration of the rotating shaft, the actuator By strengthening the bearing support force of the rotating shaft, the bearing supporting rigidity is increased, and the shaft vibration of the rotating shaft can be appropriately suppressed.

  According to the compressor of the fourth aspect of the present invention, the bearing is provided with a plurality of bearing pads divided in the circumferential direction so as to support the rotating shaft, and the actuator changes the pressing force of the bearing pad against the rotating shaft. When the vibration detecting means detects the shaft vibration of the rotating shaft, the actuator strengthens the pressing force of the plurality of bearing pads against the rotating shaft, thereby increasing the bearing support rigidity and appropriately suppressing the shaft vibration of the rotating shaft. be able to.

  According to the compressor of the fifth aspect of the invention, the bearing pad having a cylindrical shape is provided on the bearing so as to support the rotating shaft, and the actuator changes the pressing force of the bearing pad against the rotating shaft by deforming the bearing pad. Therefore, by deforming the bearing and increasing the pressing force of the plurality of bearing pads against the rotating shaft, the actuator can increase the support rigidity of the bearing and appropriately suppress the shaft vibration of the rotating shaft.

  According to the compressor of the sixth aspect of the present invention, the bearing is a magnetic bearing that supports the rotating shaft by the repulsive force or attractive force of the magnetic field, and as the support stiffness changing means, the repulsive force or the current supplied to the magnetic bearing is controlled. Since the magnetic bearing controller for changing the attractive force is provided, when the axial vibration detecting means detects the axial vibration of the rotating shaft, the magnetic bearing controller controls the current supplied to the magnetic bearing to increase the repulsive force or attractive force. Thus, the support rigidity of the bearing is increased, and the shaft vibration of the rotating shaft can be appropriately suppressed.

  According to the compressor of the seventh aspect of the present invention, the non-contact type seal mechanism is provided between the casing and the rotary shaft, and the fluid in the direction opposite to the rotation direction of the rotary shaft with respect to the seal gap in the non-contact type seal mechanism is provided. The control means controls the support rigidity changing means and the fluid supply means based on the shaft vibration of the rotating shaft detected by the shaft vibration detecting means, so that the shaft vibration detecting means rotates. When detecting the shaft vibration of the shaft, the control means controls the support rigidity changing means based on the shaft vibration of the rotating shaft to change the support rigidity of the rotating shaft by the bearing, and also controls the fluid supply means to make non-contact. By supplying the fluid in the direction opposite to the rotation direction of the rotary shaft with respect to the seal gap in the type seal mechanism, the shaft vibration of the rotary shaft can be appropriately suppressed.

  Embodiments of a compressor according to the present invention will be described below in detail with reference to the drawings. In addition, this invention is not limited by this Example.

  FIG. 1 is a schematic configuration diagram of a centrifugal compressor as a compressor according to Embodiment 1 of the present invention, and FIG. 2 is a graph showing bearing dynamic rigidity in the centrifugal compressor of Embodiment 1.

  In the centrifugal compressor according to the first embodiment, as shown in FIG. 1, a rotating shaft 12 passes through a hollow casing 11, and each end in the axial direction is rotatably supported by bearings 13 and 14. A plurality of impellers (moving blades) 15 are mounted on the rotating shaft 12. The casing 11 has a suction port 16 formed with respect to the impeller 15, a suction passage 17 is connected to the suction port 16, an opening / closing valve 18 is provided in the suction passage, and a discharge port 19 is formed. The discharge passage 20 is connected to the discharge port 19.

  The casing 11 is provided with an accelerometer 21 that detects the vibration of the bearing 13 as a shaft vibration detection unit that detects the shaft vibration of the rotary shaft 12. The accelerometer 21 is connected to an amplifier 22, a band pass filter 23, a frequency analyzer 24, and a controller (control means) 25. The accelerometer 21 detects axial vibration of the rotating shaft 12 by detecting vibration of the bearing 13 as acceleration. The amplifier 22 amplifies the vibration of the bearing 13 detected by the accelerometer 21, the bandpass filter 23 decomposes the vibration of the bearing 13 amplified by the amplifier 22 into a specific frequency, and the frequency analyzer 24 Based on the vibration of the bearing 13 that has been decomposed into the frequency, the level of the frequency component of the turning stall is calculated and output to the controller 25.

  In this case, in the rotating shaft 12, the frequency component of the turning stall is on the lower frequency side than the frequency component of the rotational speed, and increases as the rotational speed decreases.

  In the centrifugal compressor of the first embodiment, an oil tank 26 for storing oil as lubricating oil is provided, and an oil supply path 27 is provided from the oil tank 26 to the bearings 13 and 14. An oil pump 28 is provided in the path 27. Then, as the support rigidity changing means for changing the support rigidity of the rotating shaft 12 by the bearings 13 and 14, a lubricating oil cooling means for cooling the lubricating oil supplied to the bearings 13 and 14, specifically, an oil cooler 29 is used as the oil. The tank 26 is provided.

  The controller 25 as the control means controls the oil cooler 29 based on the shaft vibration of the bearing 13 detected by the accelerometer 21 to change the support rigidity of the rotating shaft 12 by the bearings 13 and 14. That is, since the viscosity of the oil increases as the temperature decreases, the oil can be cooled by the oil cooler 29 to increase the viscosity and increase the support rigidity of the rotating shaft 12.

  Therefore, in the centrifugal compressor of this embodiment, when the impeller 15 rotates together with the rotating shaft 12, the fluid is sucked into the casing 11 from the suction passage 17 through the suction port 16 and is increased in the process of passing through the blades of the impeller 15. The generated compressed fluid is discharged from the discharge port 19 to the discharge passage 20.

  At this time, if the rotational speed of the rotating shaft 12 is reduced to reduce the discharge flow rate, a turning stall is likely to occur. The accelerometer 21 detects the vibration of the bearing 13 as acceleration, the amplifier 22 amplifies the vibration of the bearing 13 detected by the accelerometer 21, and the bandpass filter 23 specifies the vibration of the bearing 13 amplified by the amplifier 22. The frequency analyzer 24 calculates the level of the frequency component of the turning stall based on the vibration of the bearing 13 decomposed into a specific frequency and outputs the level to the controller 25.

  When the level of the frequency component of the turning stall is higher than a predetermined value, the controller 25 operates the oil cooler 29 to cool the oil in the oil tank 26, thereby increasing the viscosity of the oil. The oil having a high viscosity is supplied to the bearings 13 and 14 through the oil supply path 27 by the oil pump 28. Then, the bearings 13 and 14 support the rotating shaft 12 through the oil that has cooled to become high viscosity, and the supporting rigidity of the rotating shaft 12 is increased, and the shaft vibration of the rotating shaft 12 is attenuated. Occurrence of turning stall is suppressed.

  That is, as shown in FIG. 2, the turning stall occurs at a predetermined frequency. However, when the oil cooler 29 is operated to cool the oil when the level of the turning stall frequency becomes high, the viscosity of the oil is reduced. As a result, the support rigidity of the rotary shaft 12 by the bearings 13 and 14 is increased.

  As described above, in the centrifugal compressor according to the first embodiment, the rotating shaft 12 is rotatably supported by the casing 11 via the bearings 13 and 14, and the impeller 15 for compressing the fluid is attached to the rotating shaft 12. An accelerometer 21 configured to detect axial vibration of the bearing 13, an oil cooler 29 that cools oil supplied to the bearings 13 and 14 to have high viscosity, and the axial vibration of the bearing 13 detected by the accelerometer 21. A controller 25 is provided that controls the operation of the oil cooler 29 to change the support rigidity of the rotary shaft 12 by the bearings 13 and 14.

  Therefore, when the accelerometer 21 detects the shaft vibration of the bearing 13, the controller 25 controls the operation of the oil cooler 29 based on the shaft vibration of the bearing 13 and increases the support rigidity of the rotating shaft 12 by the bearings 13 and 14. Thus, the shaft vibration of the rotating shaft 12 can be appropriately suppressed, and the occurrence of the turning stall can be appropriately suppressed without reducing the efficiency.

  In this case, in this embodiment, an oil cooler (lubricating oil cooling means) that cools the oil supplied to the bearings 13 and 14 is provided as the support rigidity changing means. 29, by cooling the oil supplied to the bearings 13 and 14, the viscosity of the oil decreases, the support rigidity of the rotating shaft 12 by the bearings 13 and 14 increases, and the shaft vibration of the rotating shaft 12 is appropriately suppressed. Can do.

  FIG. 3 is a schematic configuration diagram of a centrifugal compressor as a compressor according to the second embodiment of the present invention, and FIG. 4 is a detailed view of a bearing in the centrifugal compressor of the second embodiment. In addition, the same code | symbol is attached | subjected to the member which has the same function as what was demonstrated in the Example mentioned above, and the overlapping description is abbreviate | omitted.

  In the centrifugal compressor of the second embodiment, as shown in FIG. 3, the rotating shaft 12 is rotatably supported by bearings 31 and 32 in the casing 11, and a plurality of impellers 15 are attached to the rotating shaft 12. Has been. The casing 11 is provided with an accelerometer 21 that detects shaft vibration of the bearing 31. The accelerometer 21 is connected to an amplifier 22, a band pass filter 23, a frequency analyzer 24, and a controller 25.

  Further, in the centrifugal compressor of the second embodiment, the bearings 31 and 32 have the same configuration, and as shown in FIG. 4, a plurality of (this embodiment) divided in the circumferential direction so as to support the rotating shaft 12. In the example, four bearing pads 33 are provided. A hydraulic actuator 34 for changing the support force of the bearings 31 and 32 with respect to the rotary shaft 12 is provided as a support stiffness changing means for changing the support stiffness of the rotary shaft 12 by the bearings 31 and 32. The actuator 34 is disposed on the back side of each bearing pad 33 and can change the pressing force of each bearing pad 33 against the rotating shaft 12.

  The controller 25 controls each actuator 34 based on the shaft vibration of the bearing 31 detected by the accelerometer 21, thereby changing the support rigidity of the rotating shaft 12 by the bearings 31 and 32. That is, by increasing the pressing force of each bearing pad 33 by the actuator 34, the support rigidity of the rotating shaft 12 can be increased.

  Therefore, in the centrifugal compressor of this embodiment, when the impeller 15 rotates together with the rotating shaft 12, the fluid is sucked into the casing 11 from the suction passage 17 through the suction port 16 and is increased in the process of passing through the blades of the impeller 15. The generated compressed fluid is discharged from the discharge port 19 to the discharge passage 20.

  At this time, if the rotational speed of the rotating shaft 12 is reduced to reduce the discharge flow rate, a turning stall is likely to occur. The accelerometer 21 detects the vibration of the bearing 31 as acceleration, the amplifier 22 amplifies the vibration of the bearing 31 detected by the accelerometer 21, and the bandpass filter 23 specifies the vibration of the bearing 31 amplified by the amplifier 22. The frequency analyzer 24 calculates the level of the frequency component of the turning stall based on the vibration of the bearing 31 decomposed into a specific frequency and outputs the level to the controller 25. When the frequency component level of the turning stall is higher than a predetermined value, the controller 25 operates the actuator 34 to increase the pressing force of each bearing pad 33, whereby the rotary shaft 12 by the bearings 31 and 32 is increased. The support rigidity is increased, the shaft vibration of the rotating shaft 12 is attenuated, and the occurrence of turning stall is suppressed.

  As described above, in the centrifugal compressor according to the second embodiment, the accelerometer 21 that detects the shaft vibration of the bearing 31, the actuator 34 that changes the pressing force of each bearing pad 33 against the rotating shaft 12, and the accelerometer 21 are provided. A controller 25 is provided that changes the support rigidity of the rotating shaft 12 by the bearings 31 and 32 by controlling the operation of the actuator 34 based on the detected shaft vibration of the bearing 31.

  Accordingly, when the accelerometer 21 detects the shaft vibration of the bearing 31, the controller 25 controls the actuator 34 based on the shaft vibration of the bearing 31 to increase the pressing force of each bearing pad 33, and the bearings 31 and 32. By increasing the support rigidity of the rotary shaft 12 by the shaft vibration of the rotary shaft 12 can be appropriately suppressed.

  FIG. 5 is a schematic configuration diagram of a centrifugal compressor as a compressor according to Embodiment 3 of the present invention, and FIG. 6 is a detailed view of a bearing in the centrifugal compressor of Embodiment 3. In addition, the same code | symbol is attached | subjected to the member which has the same function as what was demonstrated in the Example mentioned above, and the overlapping description is abbreviate | omitted.

  In the centrifugal compressor of the third embodiment, as shown in FIG. 5, a rotating shaft 12 is rotatably supported by bearings 41 and 42 in the casing 11, and a plurality of impellers 15 are attached to the rotating shaft 12. Has been. The casing 11 is provided with an accelerometer 21 that detects shaft vibration of the bearing 41. The accelerometer 21 is connected to an amplifier 22, a band pass filter 23, a frequency analyzer 24, and a controller 25.

  Further, in the centrifugal compressor of the third embodiment, the bearings 41 and 42 have the same configuration, and have a cylindrical bearing pad 43 so as to support the rotating shaft 12 as shown in FIG. ing. Two hydraulic actuators 44 for changing the support force of the bearings 41 and 42 with respect to the rotary shaft 12 are provided as support stiffness changing means for changing the support stiffness of the rotary shaft 12 by the bearings 41 and 42. Each actuator 44 is disposed at a position opposed to the back side of the bearing pad 43 by 180 degrees, and the pressing force of the bearing pad 33 against the rotating shaft 12 can be changed by biasing the bearing pad 43.

  The controller 25 controls each actuator 44 based on the shaft vibration of the bearing 41 detected by the accelerometer 21, thereby changing the support rigidity of the rotating shaft 12 by the bearings 41 and 42. That is, by deforming the bearing pad 33 by the actuator 44 and increasing the pressing force, the support rigidity of the rotating shaft 12 can be increased.

  Therefore, in the centrifugal compressor of this embodiment, when the impeller 15 rotates together with the rotating shaft 12, the fluid is sucked into the casing 11 from the suction passage 17 through the suction port 16 and is increased in the process of passing through the blades of the impeller 15. The generated compressed fluid is discharged from the discharge port 19 to the discharge passage 20.

  At this time, if the rotational speed of the rotating shaft 12 is reduced to reduce the discharge flow rate, a turning stall is likely to occur. The accelerometer 21 detects the vibration of the bearing 41 as acceleration, the amplifier 22 amplifies the vibration of the bearing 41 detected by the accelerometer 21, and the bandpass filter 23 specifies the vibration of the bearing 41 amplified by the amplifier 22. The frequency analyzer 24 calculates the level of the frequency component of the turning stall based on the vibration of the bearing 41 decomposed to a specific frequency and outputs the level to the controller 25. When the frequency component level of the turning stall is higher than a predetermined value, the controller 25 operates the actuator 44 to deform the bearing pad 43 to increase its pressing force, thereby rotating the bearings 41 and 42. The support rigidity of the shaft 12 is increased, the shaft vibration of the rotating shaft 12 is attenuated, and the occurrence of turning stall is suppressed.

  As described above, in the centrifugal compressor according to the third embodiment, the accelerometer 21 that detects the shaft vibration of the bearing 41, the actuator 44 that changes the pressing force of the bearing pad 43 against the rotating shaft 12, and the accelerometer 21 detect it. A controller 25 is provided that changes the support rigidity of the rotating shaft 12 by the bearings 41 and 42 by controlling the actuator 44 based on the shaft vibration of the bearing 41.

  Accordingly, when the accelerometer 21 detects the shaft vibration of the bearing 41, the controller 25 controls the operation of the actuator 44 based on the shaft vibration of the bearing 41 to increase the pressing force of the bearing pad 43. By increasing the support rigidity of the rotating shaft 12, the shaft vibration of the rotating shaft 12 can be appropriately suppressed.

  FIG. 7 is a schematic configuration diagram of a centrifugal compressor as a compressor according to Embodiment 4 of the present invention. In addition, the same code | symbol is attached | subjected to the member which has the same function as what was demonstrated in the Example mentioned above, and the overlapping description is abbreviate | omitted.

  In the centrifugal compressor of the fourth embodiment, as shown in FIG. 7, a rotating shaft 12 is rotatably supported by bearings 51 and 52 in the casing 11, and a plurality of impellers 15 are attached to the rotating shaft 12. Has been. The casing 11 is provided with an accelerometer 21 that detects shaft vibration of the bearing 51. The accelerometer 21 is connected with a band pass filter 23, a frequency analyzer 24, and a controller 25.

  Further, in the centrifugal compressor of the fourth embodiment, the bearings 51 and 52 have the same configuration, and are configured by magnetic bearings that support the rotating shaft 12 by a magnetic field repulsive force (or attractive force). Although not shown, the bearings (magnetic bearings) 51 and 52 are provided with non-contact electromagnets around the rotating shaft 12 with a predetermined gap, and change the support rigidity of the rotating shaft 12 by the bearings 51 and 52. Magnetic bearing controllers 53 and 54 for controlling the current supplied to the electromagnet are connected as support rigidity changing means, and a power supply device 55 is connected to the magnetic bearing controllers 53 and 54. The magnetic bearing controllers 53 and 54 can change the repulsive force of the bearings 51 and 52 with respect to the rotating shaft 12 by changing the current value supplied to the bearings 51 and 52 (electromagnets) using the power supply device 55. . Displacement meters 56 and 57 are provided close to the bearings 51 and 52, and the detected displacements of the bearings 51 and 52 are fed back to the magnetic bearing controllers 53 and 54.

  The controller 25 changes the setting values of the magnetic bearing controllers 53 and 54 via the power supply device 55 based on the shaft vibration of the bearing 51 detected by the accelerometer 21, thereby supporting the rotation shaft 12 by the bearings 51 and 52. To change. In other words, the magnetic bearing controllers 53 and 54 can control the current value supplied to the electromagnet to be increased to increase the repulsive force by the bearings 51 and 52 and increase the support rigidity of the rotating shaft 12.

  Therefore, in the centrifugal compressor of this embodiment, when the impeller 15 rotates together with the rotating shaft 12, the fluid is sucked into the casing 11 from the suction passage 17 through the suction port 16 and is increased in the process of passing through the blades of the impeller 15. The generated compressed fluid is discharged from the discharge port 19 to the discharge passage 20.

  At this time, if the rotational speed of the rotating shaft 12 is reduced to reduce the discharge flow rate, a turning stall is likely to occur. The accelerometer 21 detects the vibration of the bearing 51 as acceleration, the bandpass filter 23 decomposes the vibration of the bearing 51 detected by the accelerometer 21 into a specific frequency, and the frequency analyzer 24 decomposes into a specific frequency. Based on the vibration of the bearing 51, the level of the frequency component of the turning stall is calculated and output to the controller 25. When the frequency component level of the turning stall is higher than a predetermined value, the controller 25 changes the set value of the magnetic bearing controllers 53 and 54 to increase the current value supplied to the electromagnet, and the bearings 51 and 52. By increasing the repulsive force caused by the above, the support rigidity of the rotating shaft 12 by the bearings 51 and 52 is increased, the shaft vibration of the rotating shaft 12 is reduced, and the occurrence of turning stall is suppressed.

  As described above, in the centrifugal compressor according to the fourth embodiment, the bearings 51 and 52 that support the rotating shaft 12 are configured by magnetic bearings, and the accelerometer 21 that detects the shaft vibration of the bearing 51 and the bearings 51 and 52. By changing the set values of the magnetic bearing controllers 53 and 54 based on the shaft vibration of the bearing 51 detected by the accelerometer 21 and the magnetic bearing controllers 53 and 54 for controlling the current supplied to the electromagnets of the bearings 51 and 52 A controller 25 for changing the support rigidity of the rotary shaft 12 is provided.

  Accordingly, when the accelerometer 21 detects the shaft vibration of the bearing 51, the controller 25 changes the set values of the magnetic bearing controllers 53 and 54 based on the shaft vibration of the bearing 51 to increase the repulsive force of the bearings 51 and 52. And the shaft vibration of the rotating shaft 12 can be suppressed appropriately by making the support rigidity of the rotating shaft 12 by these bearings 51 and 52 high.

  FIG. 8 is a schematic configuration diagram of a centrifugal compressor as a compressor according to Embodiment 5 of the present invention, and FIG. 9 is a detailed view of a labyrinth seal mechanism in the centrifugal compressor of Embodiment 5. In addition, the same code | symbol is attached | subjected to the member which has the same function as what was demonstrated in the Example mentioned above, and the overlapping description is abbreviate | omitted.

  In the centrifugal compressor of the fifth embodiment, as shown in FIG. 8, a rotating shaft 12 is rotatably supported by bearings 13 and 14 in the casing 11, and a plurality of impellers 15 are attached to the rotating shaft 12. Has been. Further, the casing 11 is provided with an accelerometer 21 that detects axial vibration of the bearing 13. The accelerometer 21 is connected to an amplifier 22, a band pass filter 23, a frequency analyzer 24, and a controller 25.

  In the centrifugal compressor of the fifth embodiment, a labyrinth seal 61 as a non-contact type sealing mechanism is provided between the casing 11 and the rotary shaft 12. As shown in FIG. 9, the labyrinth seal 61 fixes a bush with a labyrinth to the bearing to maintain a narrow gap S from the outer periphery of the rotary shaft 12 and prevent fluid leakage from the bearings 13 and 14. is there. Two shunt holes 62 for supplying air (fluid) in the direction opposite to the rotation direction of the rotary shaft 12 are provided in the gap S between the labyrinth seal 61 and the rotary shaft 12. A valve 63 is provided. Each of the shunt holes 62 is connected to an air supply device 64 as a fluid supply means at the base end portion, and can supply air in the tangential direction of the rotary shaft 12.

  The controller 25 controls the air supply device 64 based on the shaft vibration of the bearing 13 detected by the accelerometer 21, thereby suppressing the occurrence of turning stall due to the shaft vibration of the rotating shaft 12.

  Therefore, in the centrifugal compressor of this embodiment, when the impeller 15 rotates together with the rotating shaft 12, the fluid is sucked into the casing 11 from the suction passage 17 through the suction port 16 and is increased in the process of passing through the blades of the impeller 15. The generated compressed fluid is discharged from the discharge port 19 to the discharge passage 20.

  At this time, if the rotational speed of the rotary shaft 12 is decreased to reduce the discharge flow rate, a turning stall is likely to occur. At this time, the clearance S between the labyrinth seal 61 and the rotary shaft 12 is inserted in the rotational direction of the rotary shaft 12. There is a possibility that a fluid flow along the shaft may promote the shaft vibration due to the rotation stall. The accelerometer 21 detects the vibration of the bearing 31 as acceleration, the amplifier 22 amplifies the vibration of the bearing 31 detected by the accelerometer 21, and the bandpass filter 23 specifies the vibration of the bearing 31 amplified by the amplifier 22. The frequency analyzer 24 calculates the level of the frequency component of the turning stall based on the vibration of the bearing 31 decomposed into a specific frequency and outputs the level to the controller 25. When the level of the frequency component of the turning stall is higher than a predetermined value, the controller 25 operates the air supply device 64 and opens the on-off valve 63 to allow air to flow through each shunt hole 62 to the labyrinth seal 61 and the rotating shaft. 12 to the gap S. Then, since this air is supplied in the direction opposite to the rotation direction of the rotary shaft 12, the flow of fluid in the gap S between the labyrinth seal 61 and the rotary shaft 12 is reduced, and an increase in shaft vibration due to the rotation stall is suppressed. Is done.

  As described above, in the centrifugal compressor according to the fifth embodiment, the labyrinth seal 61 is provided between the casing 11 and the rotary shaft 12, and the rotary shaft 12 has a gap S between the labyrinth seal 61 and the rotary shaft 12. A shunt hole 62 for supplying air in the direction opposite to the rotation direction is provided, and an air supply device 64 is connected to the shunt hole 62 to detect the axial vibration of the bearing 13, and the bearing detected by the accelerometer 21. A controller 25 that controls the operation of the air supply device 64 based on the 13 shaft vibrations is provided.

  Accordingly, when the accelerometer 21 detects the shaft vibration of the bearing 13, the controller 25 operates the air supply device 64 based on the shaft vibration of the bearing 13, and the gap between the labyrinth seal 61 and the rotary shaft 12 through the shunt hole 62. When air is supplied to S, this air is reduced against the flow of fluid in the gap S between the labyrinth seal 61 and the rotary shaft 12, so that the generation of excitation force by the seal is reduced and the shaft vibration of the rotary shaft 12 is reduced. It can be suppressed appropriately.

  In addition, the structure of this Example 5 can suppress a turning stall effectively by providing with the Examples 1-4 mentioned above.

  In each of the above-described embodiments, the accelerometer 21 that detects the vibrations of the bearings 13, 31, and 41 is used as the shaft vibration detection unit that detects the shaft vibration of the rotating shaft 12. A pressure gauge that detects the pressure may be used. In this case, the pressure detected by the pressure gauge is decomposed into a specific frequency by the bandpass filter 23, and the frequency analyzer 24 calculates the level of the frequency component of the turning stall. . Moreover, you may detect the axial vibration of the rotating shaft 12 directly.

  The compressor according to the present invention can appropriately suppress the occurrence of a rotating stall without reducing the efficiency by changing the support rigidity of the rotating shaft by the bearing. It is useful for compressors.

It is a schematic block diagram of the centrifugal compressor as a compressor which concerns on Example 1 of this invention. 3 is a graph showing bearing dynamic rigidity in the centrifugal compressor of Example 1. It is a schematic block diagram of the centrifugal compressor as a compressor which concerns on Example 2 of this invention. 6 is a detailed view of a bearing in the centrifugal compressor of Example 2. FIG. It is a schematic block diagram of the centrifugal compressor as a compressor concerning Example 3 of the present invention. 6 is a detailed view of a bearing in the centrifugal compressor of Example 3. FIG. It is a schematic block diagram of the centrifugal compressor as a compressor which concerns on Example 4 of this invention. It is a schematic block diagram of the centrifugal compressor as a compressor concerning Example 5 of the present invention. FIG. 10 is a detailed view of a labyrinth seal mechanism in a centrifugal compressor according to a fifth embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Casing 12 Rotating shaft 13, 14, 31, 32.41, 42, 51, 52 Bearing 15 Impeller 21 Accelerometer (Axial vibration detection means)
25 Controller (control means)
26 Oil tank 27 Oil supply path 28 Oil pump 29 Oil cooler (support rigidity changing means, lubricating oil cooling means)
33, 43 Bearing pad 34, 44 Actuator (support stiffness changing means)
53, 54 Magnetic bearing controller 55 Power supply 61 Labyrinth seal (non-contact seal mechanism)
62 shunt hole 64 air supply device (fluid supply device)

Claims (7)

  In a compressor in which a rotating shaft is rotatably supported by a casing via a bearing and an impeller for compressing fluid is mounted on the rotating shaft, shaft vibration detecting means for detecting shaft vibration of the rotating shaft, and the bearing Support stiffness changing means for changing the support stiffness of the rotary shaft, and support of the rotary shaft by the bearing by controlling the support stiffness changing means based on the shaft vibration of the rotary shaft detected by the shaft vibration detecting means. A compressor comprising control means for changing rigidity.   2. The compressor according to claim 1, wherein the support rigidity changing unit includes a lubricating oil cooling unit that cools the lubricating oil supplied to the bearing. 3.   The compressor according to claim 1, wherein the support rigidity changing unit includes an actuator that changes a support force of the bearing with respect to the rotating shaft.   The compressor according to claim 3, wherein the bearing has a plurality of bearing pads divided in a circumferential direction so as to support the rotating shaft, and the actuator has a pressing force of the bearing pad against the rotating shaft. Compressor characterized by changing.   4. The compressor according to claim 3, wherein the bearing has a cylindrical bearing pad so as to support the rotating shaft, and the actuator deforms the bearing pad to deform the bearing with respect to the rotating shaft. A compressor characterized by changing a pressing force of a pad.   2. The compressor according to claim 1, wherein the bearing is a magnetic bearing that supports the rotating shaft by a repulsive force or an attractive force of a magnetic field, and the support rigidity changing unit controls a current supplied to the magnetic bearing. And a magnetic bearing controller for changing the repulsive force or the attractive force.   The compressor according to any one of claims 1 to 6, wherein a non-contact seal mechanism is provided between the casing and the rotary shaft, and the rotary shaft with respect to a seal gap in the non-contact seal mechanism. Fluid supply means for supplying a fluid in a direction opposite to the rotation direction of the rotation control means, and the control means controls the support stiffness changing means based on the shaft vibration of the rotation shaft detected by the shaft vibration detection means, and A compressor characterized by controlling the fluid supply means.

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