JP5078680B2 - Turbo compressor and turbo refrigerator - Google Patents

Description

  The present invention relates to a turbo compressor and a turbo refrigerator, and more particularly, to a roller bearing that employs an under-lace lubrication type rolling bearing as a bearing for a rotating shaft.

Patent Document 1 discloses a turbo compressor used in a turbo refrigerator, to which a rolling bearing with a small mechanical loss is applied in order to enable operation at high speed rotation.
Further, Patent Document 2 discloses a machine tool in which an under-lace lubrication type rolling bearing in which lubricating oil is supplied into the bearing by centrifugal force along the inner ring of the bearing with respect to the main shaft of the machine tool is disclosed. .

Japanese Patent Application Laid-Open No. 2000-291587 JP-A-8-309644

In order to improve the performance of the turbo compressor by rotating it at a higher speed, it is conceivable to employ an under-lace lubrication type rolling bearing, but there are the following problems.
In the under-race lubrication method, the amount of lubricating oil supplied to the inside of the bearing is determined by centrifugal force, so that there may be a case where the amount of supplied oil is not appropriate for the operating state.

  This invention is made | formed in view of such a situation, Comprising: It aims at providing the turbo compressor and turbo refrigerator which can supply the appropriate amount of lubricating oil according to the driving | running state.

In order to solve the above problems, the turbo compressor and the turbo refrigerator of the present invention employ the following means.
That is, the turbo compressor according to the present invention is a turbo compressor in which an impeller is provided on at least one end of a rotating shaft that is rotatably supported by a housing via a rolling bearing and is rotated at a variable speed by a drive source. The rolling bearing is an under-lace lubrication type rolling bearing in which lubricating oil is supplied to the inside of the bearing by centrifugal force along the inner ring. A mechanism is provided, and when the rotation speed of the rotating shaft is less than the first rotation speed, the oil supply mechanism supplies an excessively small oil supply amount less than the amount of lubricating oil supplied to the rolling bearing by centrifugal force. It is controlled to do.

When the rotational speed of the rotary shaft is relatively low, such as less than the first rotational speed, stirring loss is reduced by setting the amount of lubrication smaller than the amount of lubricating oil supplied to the rolling bearing by centrifugal force. The operation can be performed with the bearing loss reduced as much as possible.
The supply amount of the lubricating oil is preferably performed by controlling the oil supply pressure.

  Furthermore, the turbo compressor of the present invention is characterized in that the first rotational speed is a rotational speed at which an outer ring temperature of the rolling bearing exceeds a threshold value.

  The rotational speed at which the outer ring temperature of the rolling bearing exceeds the threshold value is set as the first rotational speed, and if the rotational speed is less than the first rotational speed, the operation is continued with low loss as described above. That is, when the rotation speed is less than the first rotation speed, the low-loss operation is prioritized by allowing the outer ring temperature to rise.

  Furthermore, the turbo compressor of the present invention is characterized in that the oil supply mechanism is controlled based on data in which an oil supply amount that minimizes bearing loss is determined in accordance with the rotational speed of the rotary shaft.

  By operating the feed amount that minimizes the bearing loss based on the data determined according to the rotational speed of the rotating shaft and performing feedforward control, stable control can be performed.

  Furthermore, the turbo compressor of the present invention is characterized in that a rated rotational speed of the rotating shaft is set to be less than the first rotational speed.

  By setting the rated rotational speed of the rotary shaft to be less than the first rotational speed, it is possible to always operate with low loss during rated operation.

  Further, in the turbo compressor according to the present invention, the outer ring temperature of the rolling bearing is controlled by the oil supply temperature of the lubricating oil so as to become a set outer ring temperature corresponding to the rotation speed of the rotating shaft, and the rotation of the rotating shaft When the number is less than the first rotational speed, the oil supply temperature is controlled so that the outer ring temperature is corrected based on the current value temperature of the outer ring even when the set outer ring temperature is exceeded. It is characterized by doing.

When the rotational speed of the rotating shaft is less than the first rotational speed, the rotational speed is relatively low, so that an increase in the outer ring temperature is acceptable. Therefore, even when the outer ring temperature exceeds the set outer ring temperature corresponding to the rotational speed of the rotating shaft, the lubricating oil supply temperature is controlled so that the outer ring temperature is corrected based on the current temperature of the outer ring. By doing so, it was decided to control without increasing the amount of oil supply. Thereby, the driving | operation with a low loss can be continued.
In addition, when the turbo compressor is applied to a turbo refrigerator, the outer ring temperature may exceed the set outer ring temperature during heating operation in the cold season of winter or continuous frost operation, which is particularly effective in this case.

  Further, the turbo compressor according to the present invention is the turbo compressor in which the housing is rotatably supported via a rolling bearing and the impeller is provided at least at one end of a rotating shaft that is rotated at a variable speed by a driving source. The bearing is an under-lace lubrication type rolling bearing in which lubricating oil is supplied to the inside of the bearing by centrifugal force along the inner ring, and the rolling bearing includes an oil supply mechanism that adjusts the amount of lubricating oil supplied to the bearing. When the rotational speed of the rotating shaft is equal to or higher than the first rotational speed, the oil supply mechanism supplies an excessive oil supply amount that is greater than the amount of lubricating oil supplied into the rolling bearing by centrifugal force. It is controlled as follows.

  When the rotating shaft is operated at a relatively high speed, the amount of lubrication aimed at low-loss operation with as little agitation loss as possible is sufficient for the bearing to generate sufficient heat because the absolute amount of lubrication is insufficient. The bearing temperature rises without being able to be removed. Therefore, in the present invention, when the rotational speed of the rotary shaft is relatively high, such as the first rotational speed or more, the amount of lubricating oil supplied into the rolling bearing by centrifugal force while allowing agitation loss. An excessive increase in the amount of oil to be supplied prevents excessive increase in bearing temperature.

  Furthermore, the turbo compressor according to the present invention is a turbo compressor in which an impeller is provided at least at one end of a rotating shaft that is rotatably supported by a housing via a rolling bearing and is rotated at a variable speed by a drive source. The bearing is an under-lace lubrication type rolling bearing in which lubricating oil is supplied to the inside of the bearing by centrifugal force along the inner ring, and the rolling bearing includes an oil supply mechanism that adjusts the amount of lubricating oil supplied to the bearing. When the rotational speed of the rotating shaft is equal to or higher than the first rotational speed, the oil supply mechanism supplies an excessive oil supply amount that is greater than the amount of lubricating oil supplied into the rolling bearing by centrifugal force. It is controlled as follows.

  If the control of each of the above inventions is provided, an operation with a low loss can be performed at less than the first rotation speed, and an operation with priority given to management of the bearing temperature can be performed at the first rotation speed or more.

  Furthermore, in the turbo compressor according to the present invention, the first rotational speed is a rotational speed at which an outer ring temperature of the rolling bearing exceeds a threshold value.

  The rotation speed at which the outer ring temperature of the rolling bearing exceeds the threshold value is set as the first rotation speed, and the operation for managing the outer ring temperature below the predetermined value as described above is continued at the first rotation speed or higher.

  Further, in the turbo compressor according to the present invention, the oil supply mechanism is controlled based on data in which an oil supply amount that keeps the outer ring temperature of the rolling bearing below the threshold value is determined in accordance with the rotational speed of the rotary shaft. Features.

  Stable control can be performed by operating the feed amount to maintain the outer ring temperature of the rolling bearing below the threshold value based on the data determined in accordance with the rotational speed of the rotary shaft and performing feedforward control.

  A turbo chiller according to the present invention includes any one of the above-described turbo compressors as a turbo compressor constituting a refrigeration cycle.

  By using a turbo refrigerator equipped with the turbo compressor of each of the above inventions, operation with low bearing loss is realized at low rotation speeds, and operation in which the outer ring temperature of the rolling bearing is controlled at high rotation speeds. Realized.

  Furthermore, the turbo refrigerator of the present invention is characterized in that when the outer ring temperature of the rolling bearing exceeds the threshold value, the output of the turbo refrigerator is reduced.

  When the outer ring temperature of the rolling bearing exceeded the threshold value, the outer ring temperature was reduced by reducing the output of the turbo refrigerator. As a result, failure around the rolling bearing or rolling bearing can be prevented. In order to reduce the output of the turbo chiller, for example, the inlet vane for adjusting the amount of refrigerant sucked into the turbo compressor may be throttled.

According to the present invention, the following operational effects can be obtained.
When the rotational speed of the rotating shaft of the turbo compressor is lower than the first rotational speed, the operation can be performed with the bearing loss of the rolling bearing reduced.
Moreover, when the rotation speed of the rotating shaft of the turbo compressor is higher than the first rotation speed, an excessive increase in bearing temperature can be prevented.

An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a longitudinal sectional view of a turbo compressor 1 according to an embodiment of the present invention. The turbo compressor 1 includes a housing 2 configured by integrally connecting a compressor side housing 2A and a motor side housing 2B. An electric motor 3 that is driven at a variable speed via an inverter device (not shown) is incorporated in the motor-side housing 2B. One end of the motor shaft 3A of the electric motor 3 projects from the motor side housing 2B to the compressor side housing 2A.

  A refrigerant gas suction port 5 having a variable guide vane 4 is formed in the compressor-side housing 2A, and a first-stage compression stage 6 and a second-stage compression are provided in a downstream flow path following the suction port 5. Stages 7 are sequentially provided. The first stage compression stage 6 is provided with a diffuser part 8, a return vent 9 and a guide vane 10, and the second stage compression stage 7 is provided with a diffuser part 11 and a scroll chamber 12. The compressed refrigerant gas is discharged from the scroll chamber 12 through a discharge port (not shown).

  In addition, a rotary shaft 13 is rotatably installed in the compressor-side housing 2A, and a first stage impeller 14 for the first stage compression stage 6 and a second stage are provided on one end side of the rotary shaft 13. A second stage impeller 15 for the compression stage 7 is provided. The rotary shaft 13 is supported by a rolling bearing 17 consisting of a plurality of angular ball bearings, the central portion of which is installed in the compressor-side housing 2A via a bearing box 16, and the other end is connected to the motor side via a bearing box 18. It is supported by a rolling bearing 19 composed of a plurality of angular ball bearings installed in the housing 2B.

  A small-diameter gear 20 is provided at an intermediate portion of the rotary shaft 13 supported by the rolling bearings 17 and 19. The gear 20 is meshed with a large-diameter gear 21 provided at one end of the motor shaft 3A, and a speed increasing mechanism 22 is configured by these gears 20 and 21.

  As shown in FIG. 2, the rolling bearings 17 and 19 that support the rotating shaft 13 are provided with scoops 31 having a plurality of nozzle holes 32 at equal intervals along the circumferential direction on the inner ring 35 side. Lubricating oil is supplied to the scoop 31 from an oil supply hole 34 (see FIG. 1) provided in the housing 2 via a fixed side spacer 33 having an oil supply hole 33A and a nozzle hole 33B and the bearing boxes 16 and 18. Configured to be The lubricating oil supplied to the scoop 31 is supplied into the bearing by centrifugal force along the inclination of the inner ring 35 of the rolling bearings 17 and 19 from the nozzle hole 32 of the scoop 31, and the inner ring 35, the outer ring 36, and the ball 37. An oil film is formed between them to lubricate the rolling bearings 17 and 19. In this way, the rolling bearings 17 and 19 of the under race lubrication system are configured. The lubricating oil that has lubricated the rolling bearings 17 and 19 is discharged into the housing 2, and returned to the oil tank 39 (see FIG. 3) through the oil drain hole 38 provided in the housing 2.

  FIG. 3 shows the configuration of the oil supply mechanism 40 for the rolling bearings 17 and 19. The oil supply mechanism 40 includes an oil supply line 41 that supplies the lubricating oil in the oil tank 39 to the oil supply hole 34, an oil supply pump 42 that sends the lubricant to the oil supply line 41, and an inverter-driven motor 43 that drives the oil supply pump 42 at a variable speed. And the relief line 44 for returning the lubricating oil sent from the oil supply pump 42 to the oil supply line 41 to the oil tank 39, the control valve 45 provided in the relief line 44, and the lubricating oil supplied via the oil supply line 41 are cooled. The oil cooler 46 and the refrigerant that serves as a cooling heat source for the oil cooler 46 are placed in an appropriate place in the refrigeration cycle of the turbo refrigerator (the refrigerant pipe between the reservoir in the condenser and the reservoir in the evaporator constituting the refrigeration cycle). System or component equipment), a refrigerant system path 47 that is branched and introduced, a flow rate adjustment valve 48 that is provided in the refrigerant system path 47, and a pressure that detects the lubrication oil supply pressure. Based on the detected values of the sensor 49, the temperature sensor 50 for detecting the lubricating oil supply temperature, the temperature sensor 51 for detecting the temperature of the outer ring 36 of the rolling bearings 17 and 19, and the detected values of the pressure sensor 49 and the temperature sensors 50 and 51. The control unit 52 controls the number of rotations of the oil supply pump 42 (motor 43) and the opening degree of the control valve 45 and the flow rate adjusting valve 48.

  The control unit 52 detects the rotational speed of the rotary shaft 13 and the oil supply pressure, and the rotational speed of the oil supply pump 42 based on the relationship between the oil supply amount and the oil supply pressure corresponding to the preset rotational speed of the rotary shaft 13. Alternatively, the oil supply pressure is controlled by the opening degree of the control valve 45 or both, and the oil supply amount to the rolling bearings 17 and 19 is controlled according to the rotational speed of the rotary shaft 13.

Specifically, the amount of oil supply is controlled based on a map (data) as shown in FIG. The map shown in the figure is obtained by a trial run performed in advance for each model of the turbo compressor 1.
In general, in an under-race lubrication type rolling bearing, assuming a case where oil supply is performed only by centrifugal force, the oil supply amount Q is proportional to the rotational speed N as shown by a straight line A in FIG. Further, the heat generation of the rolling bearing can be expressed by the power of the rotational speed. Therefore, in order to keep the outer ring temperature of the rolling bearing constant, the amount of oil supply Q is expressed as a power of N (Q = k2N ^{1.4 in} the case shown in the figure) as shown by curve B in FIG.

  On the other hand, when an oil film necessary and sufficient for lubrication is formed between the balls 37 and the inner ring 35 and the outer ring 36, almost no agitation loss occurs, so that the loss of the rolling bearing is minimized. The straight line C shows the amount of oil supply Q at this time.

  As can be seen by comparing the straight line A, the curved line B, and the straight line C, it can be seen that at a relatively low speed, if the straight line C is selected, an operation with the least amount of oil supply and the least loss is possible. In other words, a highly efficient operation can be realized positively by selecting an under-lubricating amount (straight line C) that is smaller than the case where lubricating oil is supplied only by centrifugal force as the under-lace lubrication method (straight line A). Can do.

  However, on the straight line C, since the amount of oil supply is small, the outer ring temperature of the rolling bearing rises. This is apparent from the fact that the straight line C is lower than the curved line B at the oil supply amount Q. Therefore, when the first rotation speed N1 is set as a threshold value and the first rotation speed N1 is exceeded, the curve B is selected, and the oil supply amount is controlled to be constant without increasing the outer ring temperature of the rolling bearing. That is, at the first rotational speed N1 or higher, by supplying an excessive oil supply amount that is larger than the amount (straight line A) in which the lubricating oil is supplied into the rolling bearing only by centrifugal force while allowing agitation loss, Prevent excessive increase in outer ring temperature.

The first rotation speed N1 is preferably set to a rotation speed at which the outer ring temperature exceeds a predetermined threshold (for example, a temperature allowed as the outer ring temperature, which is 85 ° C. in the present embodiment).
Moreover, it is preferable to set the rated rotation speed of the rotating shaft 13 to be less than the first rotation speed. Thereby, it is possible to always operate with low loss during rated operation.

Further, the control unit 52 detects the temperature of the outer ring 36 of the rolling bearings 17 and 19 and adjusts the oil supply temperature by the oil cooler 46 so that the outer ring temperature becomes a predetermined value. The oil supply temperature can be adjusted by controlling the flow rate of the refrigerant introduced into the oil cooler 46 through the refrigerant path 47 by the flow rate adjusting valve 48. In this way, by adjusting the oil supply temperature to control the outer ring temperature of the rolling bearings 17 and 19 to a predetermined value, it is not necessary to supply the lubricant excessively for cooling the bearing, and the oil supply amount can be used for lubrication. It becomes possible to suppress to the necessary minimum amount.
The control of the oil supply temperature is performed as shown in FIG. 5 using the first rotational speed N1 of the rotating shaft 13 employed in FIG. That is, as shown in FIG. 5, at a low rotation speed less than the first rotation speed N1, the outer ring temperature is set to a temperature proportional to the rotation speed, and this is set as a low rotation set outer ring temperature TL. On the other hand, at a high rotational speed equal to or higher than the first rotational speed N1, an allowable outer ring temperature (for example, 85 ° C.) is set to a constant temperature regardless of the rotational speed, and this is set as a high rotational set outer ring temperature TH. By properly using the outer ring temperature in this way, emphasis is placed on realizing low-loss operation while allowing the outer ring temperature to rise in accordance with the number of revolutions at low revolutions, and not exceeding the allowable value of the outer ring temperature at high revolutions. Control that emphasizes continuous and stable operation.

Next, the operation of the turbo compressor 1 having the above configuration will be described.
When the electric motor 3 is driven and the motor shaft 3 </ b> A is rotated, the rotation is increased by the speed increasing mechanism 22 configured by the gear 21 provided at one end thereof and the gear 20 meshing with the gear 21. Is rotated at high speed. When the rotating shaft 13 is rotated, the first stage impeller 14 and the second stage impeller 15 are rotated, and the compression operation is started. The refrigerant gas sucked into the turbo compressor 1 from the suction port 5 through the variable guide vane 4 by the rotation of the first stage impeller 14 and the second stage impeller 15 is converted into the first stage compression stage 6 and the second stage compression stage. 7 is compressed in two stages. The two-stage compressed high-pressure refrigerant gas is discharged from the scroll chamber 12 to the outside of the compressor through a discharge port (not shown). This high-pressure refrigerant gas circulates in the refrigeration cycle of a turbo chiller including the turbo compressor 1 and a condenser, a decompression device, an evaporator (not shown), and the like, thereby achieving a required refrigeration effect.

  On the other hand, a required amount of lubricating oil is supplied from the oil supply mechanism 40 to the rolling bearings 17 and 19 that support the rotating shaft 13. The lubricating oil is supplied to the scoop 31 from the oil supply line 41 of the oil supply mechanism 40 through the oil supply holes 34, the bearing housings 16 and 18, and the fixed side spacer 33, and the inner ring 35 is inclined from the plurality of nozzle holes 32 of the scoop 31. The oil is fed into the bearing along

  That is, the control unit 52 controls the number of rotations of the oil supply pump 42 or the control valve 45 provided in the relief line 44 based on the oil supply pressure set in advance corresponding to the oil supply amount proportional to the number of rotations of the rotary shaft 13. The oil supply pressure is controlled by the opening degree or both, and the oil supply amount from the oil supply mechanism 40 to the rolling bearings 17 and 19 is adjusted. As a result, the desired lubricating oil can be supplied to the rolling bearings 17 and 19 in response to fluctuations in the rotational speed of the rotating shaft 13.

  Further, the control unit 52 adjusts the oil supply temperature of the lubricating oil supplied from the oil supply mechanism 40 to the rolling bearings 17 and 19 to control the temperature of the outer ring 36 in the rolling bearings 17 and 19 to be constant. That is, the control unit 52 detects the outer ring temperature of the rolling bearings 17 and 19 by the temperature sensor 51, detects the oil supply temperature by the temperature sensor 50, and determines the refrigerant flow rate introduced into the oil cooler 46 through the refrigerant system path 47. By adjusting the flow rate adjusting valve 48 to control the cooling capacity of the oil cooler 46, the oil supply temperature of the lubricating oil is adjusted, and the temperature of the outer ring 36 is controlled to be constant.

Next, a control method for supplying lubricating oil to the rolling bearings 17 and 19 will be described with reference to FIG.
During operation, in step S1, the rotational speed of the rotary shaft 13 is obtained, and it is determined whether or not the rotational speed is less than the first rotational speed N1.
[At low rotation]
When the rotational speed of the rotary shaft 13 is less than the first rotational speed N1 (YES), the process proceeds to step S2, and the set outer ring temperature during low rotation according to the rotational speed of the rotary shaft 13 from the map shown in FIG. Get TL. In step S2, an oil supply amount Q (= k1N) corresponding to the rotational speed of the rotary shaft 13 is obtained from the map shown in FIG. In this case, an oil supply amount Q that realizes low loss is selected. The oil is supplied from the oil supply mechanism 40 to the rolling bearings 17 and 19 by the control unit 52 so as to satisfy the oil supply amount Q (feed forward control).
And it progresses to step S3 and it is determined whether the lubricating oil temperature Toils is higher than the setting lubricating oil temperature Tset. The lubricating oil temperature Toils is obtained by the temperature sensor 50 shown in FIG. If the lubricating oil temperature Toils is equal to or lower than the set lubricating oil temperature Tset (NO), the process proceeds to step S4, and whether or not the current outer ring temperature T is higher than the low rotation set outer ring temperature TL obtained in step S2. Determine whether. The current outer ring temperature T is obtained by the temperature sensor 51 shown in FIG. When the current outer ring temperature T is higher than the low rotation set outer ring temperature TL (YES), the process proceeds to step S5, and the lubricating oil temperature is fed back so that the outer ring temperature T becomes equal to the low rotation set outer ring temperature TL. Control. As described above, the adjustment of the outer ring temperature T is performed by controlling the cooling capacity of the oil cooler 46 (see FIG. 3). That is, the operation with a low loss is realized without changing the supply amount Q of the lubricating oil. In step S4, when the current outer ring temperature T is equal to or lower than the set outer ring temperature TL during low rotation (NO), the outer ring temperature is sufficiently cooled, so the operation is continued as it is (return).

  On the other hand, if the lubricating oil temperature Toils is higher than the set lubricating oil temperature Tset in step S3 (YES), the process proceeds to step S6, and the lubricating oil temperature Toils and the set lubricating oil temperature are set to the low outer rotation set outer ring temperature TL. The value obtained by adding the difference value from Tset is compared with the outer ring temperature T. When the outer ring temperature T is smaller than the value obtained by adding the difference between the lubricating oil temperature Toils and the set lubricating oil temperature Tset to the set outer ring temperature TL at the time of low rotation (NO), the outer ring temperature T does not increase so much. The operation is continued as it is (return). On the other hand, when the outer ring temperature T is larger than the value obtained by adding the difference value between the lubricating oil temperature Toils and the set lubricating oil temperature Tset to the low rotation set outer ring temperature TL (YES), the process proceeds to step S7, and the outer ring Feedback control is performed so that the temperature T becomes a value obtained by adding a difference value between the lubricating oil temperature Toils and the set lubricating oil temperature Tset to the set outer ring temperature TL during low rotation. At this time, similarly to step S5, the temperature is adjusted by controlling the cooling capacity of the oil cooler 46 (see FIG. 3), and the supply amount Q of the lubricating oil is not changed. The control in step S7 has the following advantages. When the rotation speed of the rotating shaft 13 is less than the first rotation speed N1, the rotation speed is relatively low, so that an increase in the outer ring temperature is allowable. Therefore, even when the outer ring temperature exceeds the low-set outer ring temperature TL corresponding to the number of rotations of the rotating shaft, the lubricant oil is adjusted so that the outer ring temperature is corrected based on the current value temperature of the outer ring. By controlling the oil supply temperature, the oil supply amount was controlled without increasing. Thereby, the driving | operation with a low loss can be continued. In addition, when the turbo compressor is applied to a turbo chiller as in this embodiment, the outer ring temperature may exceed the set outer ring temperature during heating operation or frost continuation operation in the cold season of winter. This control is particularly effective.

[High rotation]
If the rotational speed of the rotary shaft 13 is greater than or equal to the first rotational speed N1 in step S1 (NO), the process proceeds to step S10, and a high value corresponding to the rotational speed of the rotary shaft 13 is obtained from the map shown in FIG. The set outer ring temperature TH during rotation is obtained. That is, the set outer ring temperature TH at the time of high rotation is set constant at 85 ° C. in the present embodiment. In step S2, an oil supply amount Q (= k2N ^a ) corresponding to the rotational speed of the rotary shaft 13 is obtained from the map shown in FIG. In this case, the oil supply amount Q is selected with emphasis on the management of the outer ring temperature while allowing the stirring loss. The oil is supplied from the oil supply mechanism 40 to the rolling bearings 17 and 19 by the control unit 52 so as to satisfy the oil supply amount Q (feed forward control).

  Then, the process proceeds to step S11, and it is determined whether or not the current outer ring temperature T is higher than the high rotation set outer ring temperature TH obtained in step S10. The current outer ring temperature T is obtained by the temperature sensor 51 shown in FIG. If the current outer ring temperature T is higher than the set outer ring temperature TH during high rotation (YES), the process proceeds to step S12, and the lubricating oil temperature is fed back so that the outer ring temperature T becomes equal to the set outer ring temperature TH during high rotation. Control. As described above, the adjustment of the outer ring temperature T is performed by controlling the cooling capacity of the oil cooler 46 (see FIG. 3). That is, the supply amount Q of the lubricating oil is not changed. In step S11, when the current outer ring temperature T is equal to or lower than the set outer ring temperature TH during high rotation (NO), the outer ring temperature does not exceed the threshold value, so the operation is continued as it is (return).

[Overload control]
Although not shown in the flowchart of FIG. 6, the following overload control is also performed.
When the outer ring temperature of the rolling bearings 17 and 19 exceeds a threshold (for example, 90 ° C.), the outer ring temperature is lowered by reducing the output of the turbo refrigerator. Thereby, failure of the rolling bearings 17 and 19 can be prevented. In order to reduce the output of the turbo chiller, for example, the variable guide vane 4 (inlet vane, see FIG. 1) for adjusting the amount of refrigerant sucked into the turbo compressor 1 may be throttled.

According to this embodiment, the following effects are produced.
When the rotational speed of the rotary shaft 13 is relatively low, such as less than the first rotational speed N1, the amount of lubrication is less than the amount of lubricating oil supplied into the rolling bearing by centrifugal force. The operation can be performed with the stirring loss reduced as much as possible and the bearing loss reduced.
In addition, stable control is possible by operating the feed amount Q that minimizes the bearing loss based on the data (see FIG. 4) determined according to the rotational speed of the rotary shaft 13 and performing feedforward control. Become.
Further, when the rotational speed of the rotary shaft 13 is relatively high, such as the first rotational speed N1 or more, the amount of lubricating oil supplied to the rolling bearing by centrifugal force is allowed while allowing agitation loss. A large amount of excessive oil supply was decided. Thereby, an excessive increase in the bearing temperature can be prevented, and a failure around the rolling bearing or the bearing can be avoided.
Further, since the oil supply amount for keeping the outer ring temperature of the rolling bearing below the threshold value is operated based on the data determined in accordance with the rotational speed of the rotary shaft 13, the feedforward control is performed, so that stable control is possible. Become.

It is a longitudinal cross-sectional view of the turbo compressor concerning one Embodiment of this invention. It is a longitudinal cross-sectional view of the rolling bearing which supports the rotating shaft of the turbo compressor shown in FIG. It is the block diagram which showed the oil supply mechanism which supplies lubricating oil to the rolling bearing which supports the rotating shaft of the turbo compressor shown in FIG. It is the graph which showed the amount of oil supply set according to rotation speed. It is the graph which showed the setting outer ring temperature set according to rotation speed. It is the flowchart which showed the oil supply control of the rolling bearing which supports the rotating shaft of the turbo compressor shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Turbo compressor 2 Housing 3 Electric motor 13 Rotating shafts 14 and 15 Impeller 17 and 19 Rolling bearing 31 Scoop 32 Nozzle hole 35 Inner ring 36 Outer ring 40 Oil supply mechanism 42 Oil supply pump 44 Relief line 45 Control valve 46 Oil cooler 48 Flow rate adjustment valve 49 Hydraulic sensor 50, 51 Temperature sensor N1 First rotation speed

Claims (11)

In a turbo compressor in which an impeller is provided on at least one end of a rotating shaft that is rotatably supported by a housing via a rolling bearing and is rotated at a variable speed by a drive source.
The rolling bearing is an under-lace lubrication type rolling bearing in which lubricating oil is supplied into the bearing by centrifugal force along the inner ring,
The rolling bearing is provided with an oil supply mechanism for adjusting the amount of lubricating oil supplied to the bearing,
The oil supply mechanism is controlled so as to supply an excessively small oil supply amount less than the amount of lubricating oil supplied into the rolling bearing by centrifugal force when the rotational speed of the rotary shaft is less than the first rotational speed. A turbo compressor characterized by that.   2. The turbo compressor according to claim 1, wherein the first rotational speed is a rotational speed at which an outer ring temperature of the rolling bearing exceeds a threshold value.   3. The turbo compressor according to claim 1, wherein the oil supply mechanism is controlled based on data in which an oil supply amount that minimizes bearing loss is determined in accordance with a rotational speed of the rotary shaft.   The turbo compressor according to any one of claims 1 to 3, wherein a rated rotational speed of the rotating shaft is set to be less than the first rotational speed. The outer ring temperature of the rolling bearing is controlled by the oil supply temperature of the lubricating oil so as to be a set outer ring temperature corresponding to the rotation speed of the rotating shaft,
When the rotational speed of the rotating shaft is less than the first rotational speed, the outer ring temperature is corrected based on the current value temperature of the outer ring even when the set outer ring temperature is exceeded. The turbo compressor according to claim 1, wherein the oil supply temperature is controlled. In a turbo compressor in which an impeller is provided on at least one end of a rotating shaft that is rotatably supported by a housing via a rolling bearing and is rotated at a variable speed by a drive source.
The rolling bearing is an under-lace lubrication type rolling bearing in which lubricating oil is supplied into the bearing by centrifugal force along the inner ring,
The rolling bearing is provided with an oil supply mechanism for adjusting the amount of lubricating oil supplied to the bearing,
The oil supply mechanism is controlled so as to supply an excessive oil supply amount greater than the amount of lubricating oil supplied into the rolling bearing by centrifugal force when the rotational speed of the rotating shaft is equal to or higher than the first rotational speed. A turbo compressor characterized by that. In a turbo compressor in which an impeller is provided on at least one end of a rotating shaft that is rotatably supported by a housing via a rolling bearing and is rotated at a variable speed by a drive source.
The rolling bearing is an under-lace lubrication type rolling bearing in which lubricating oil is supplied into the bearing by centrifugal force along the inner ring,
The rolling bearing is provided with an oil supply mechanism for adjusting the amount of lubricating oil supplied to the bearing,
The oil supply mechanism is controlled so as to supply an excessive oil supply amount greater than the amount of lubricating oil supplied into the rolling bearing by centrifugal force when the rotational speed of the rotating shaft is equal to or higher than the first rotational speed. The turbo compressor according to any one of claims 1 to 5, wherein:   The turbo compressor according to claim 6 or 7, wherein the first rotational speed is a rotational speed at which an outer ring temperature of the rolling bearing exceeds a threshold value.   9. The oil supply mechanism is controlled based on data in which an oil supply amount for keeping an outer ring temperature of the rolling bearing at or below the threshold value is determined according to the number of rotations of the rotary shaft. The turbo compressor according to crab.   A turbo refrigeration machine comprising the turbo compressor according to any one of claims 1 to 9 as a turbo compressor constituting a refrigeration cycle.   The turbo chiller according to claim 10, wherein when the outer ring temperature of the rolling bearing exceeds the threshold value, the output of the turbo chiller is reduced.

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