JP2013122331A - Refrigerator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refrigerator having a compression mechanism capable of getting out of a surging state by a simple constitution.SOLUTION: The refrigerator has the compression mechanism 2 compressing a refrigerant of a suction space S3 and a refrigerant passage connecting a discharge opening 22 and the suction space S3 and making the refrigerant discharged from the compression mechanism 2 flow to the suction space S3. The compression mechanism 2 has a compression section 24, a motor 25 driving the compression section 24 via a rotating shaft 26, a radial magnetic bearing 27 rotatably supporting the rotating shaft 26 in a non-contact manner, a motor casing 32 to which the refrigerant flowing in the refrigerant passage is supplied, second bypass piping 81 making the refrigerant in the motor casing 32 flow to the suction space S3, and an opening/closing mechanism 82 changed from a closed condition for blocking the flow-in of the refrigerant in the motor casing 32 into the suction space S3 to an opened condition for making the refrigerant flowing in the motor casing 32 flow into the suction space S3 when the heat generation quantity of the radial magnetic bearing 27 exceeds a predetermined quantity.

Description

  The present invention relates to a refrigeration apparatus.

  2. Description of the Related Art Conventionally, a centrifugal compression mechanism that compresses fluid using centrifugal force generated by rotation of an impeller has been employed in a refrigeration apparatus. While the centrifugal compression mechanism has the advantage of being able to suck and compress a large amount of fluid, if the amount of fluid to be sucked is below a predetermined amount, a phenomenon of fluctuation in discharge pressure and flow rate called surging occurs, causing vibration of the compression mechanism. There is a problem of growing.

  Therefore, for example, in the compression mechanism disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 6-346893), the pressure (suction pressure and discharge pressure), flow rate, and temperature in the compression mechanism system are detected, and a simulator and a calculator are installed. To predict the occurrence of surging. And when generation | occurrence | production of surging is estimated, suppression control is started in advance or the rotation speed of a bypass valve or a compression mechanism is controlled, and it comes out of a surging state.

  In the technique disclosed in Patent Document 1, many sensors are indispensable, and a complicated control circuit is required to be incorporated. Therefore, there is a problem that the configuration of the compression system is complicated and the manufacturing cost is increased.

  Then, the subject of this invention is providing the freezing apparatus provided with the compression mechanism which can escape from a surging state by simple structure.

  The refrigeration apparatus according to the first aspect of the present invention includes a compression mechanism and a refrigerant path. The compression mechanism compresses the refrigerant flowing through the suction space and then discharges it outside through the discharge port. The refrigerant path connects the discharge port and the suction space and allows the refrigerant discharged from the compression mechanism to flow to the suction space. The compression mechanism includes a compression unit, a motor, a magnetic bearing, a motor casing, a bypass pipe, and an opening / closing mechanism. The compression unit compresses the refrigerant. The motor is attached to a rotation shaft connected to the compression unit, and drives the compression unit via the rotation shaft. The magnetic bearing supports the rotating shaft so as to be rotatable in a non-contact manner. The motor casing contains a motor and a magnetic bearing, and is supplied with refrigerant flowing through the refrigerant path. The bypass pipe flows the refrigerant in the motor casing to the suction space. The opening / closing mechanism opens and closes the bypass pipe by switching between the open state and the closed state, and changes from the closed state to the open state when the heat generation amount of the magnetic bearing exceeds a predetermined amount. The open state is a state in which the refrigerant in the motor casing flows into the suction space. The closed state is a state in which the refrigerant in the motor casing is blocked from flowing into the suction space.

  Here, for example, when the amount of heat generated by the magnetic bearing exceeds a predetermined amount, surging occurs.

  In the present invention, when the amount of heat generated by the magnetic bearing exceeds a predetermined amount, that is, when surging occurs, a surging occurs by providing an opening / closing mechanism that changes from the closed state to the open state. Bypass piping can be opened. When the bypass pipe is opened, the refrigerant in the motor casing flows into the suction space. Thereby, the refrigerant | coolant which flows in into a compression part increases. Thus, in the present invention, it is possible to escape from the surging state with a simple configuration.

  The refrigeration apparatus according to the second aspect of the present invention is the refrigeration apparatus according to the first aspect of the present invention, and further includes a control unit that controls the amount of current flowing through the coil. The magnetic bearing has an electromagnet including a coil. The compression mechanism further includes a gap sensor that detects a gap dimension of the gap between the rotating shaft and the magnetic bearing. Further, the control unit increases the amount of current flowing through the coil when the gap size detected by the gap sensor exceeds a predetermined value.

  Here, since vibration occurs when surging occurs, the gap size detected by the gap sensor may exceed a predetermined value. When the gap size exceeds a predetermined value, the amount of current flowing through the coil increases in order to suppress vibration. That is, when surging occurs, the amount of current flowing through the coil increases, and the amount of heat generated by the magnetic bearing increases, exceeding a predetermined amount.

  Thus, when surging occurs, the amount of heat generated by the magnetic bearing exceeds a predetermined amount. Therefore, in the present invention, by providing an opening / closing mechanism that changes from a closed state to an open state when the heat generation amount of the magnetic bearing exceeds a predetermined amount, the bypass pipe is naturally opened when surging occurs. Therefore, in the present invention, it is possible to escape from the surging state with a simple configuration.

  The refrigeration apparatus according to the third aspect of the present invention is the refrigeration apparatus according to the first aspect or the second aspect of the present invention, and the opening / closing mechanism includes an opening / closing member and a contact member. The opening / closing member opens and closes the bypass pipe. The contact member is in contact with the opening / closing member and the magnetic bearing. The contact member is a temperature deformation member that deforms due to a temperature change. When the contact member is deformed when the heat generation amount of the magnetic bearing exceeds a predetermined amount, the opening / closing member changes from the open state to the closed state.

  In the present invention, since the contact member as the temperature deforming member is in contact with the magnetic bearing, the contact member can be deformed with the amount of heat generated by the magnetic bearing. Therefore, when the calorific value of the magnetic bearing exceeds a predetermined amount, the open / close member that contacts the contact member that is deformed accordingly can be changed from the open state to the closed state.

  A refrigeration apparatus according to a fourth aspect of the present invention is the refrigeration apparatus according to any one of the first to third aspects of the present invention, further comprising a radiator. The radiator is provided in the refrigerant path to radiate the refrigerant. The refrigerant that has passed through the radiator is decompressed and supplied into the motor casing.

  In this invention, since a motor can be cooled, the heat_generation | fever of a motor can be suppressed. Further, it is possible to escape from the surging state by flowing into the suction space through the bypass pipe using the refrigerant for cooling the motor.

  In the refrigeration apparatus according to the first and second aspects of the present invention, it is possible to escape from the surging state with a simple configuration.

  In the refrigeration apparatus according to the third aspect of the present invention, when the heat generation amount of the magnetic bearing exceeds a predetermined amount, the open / close member that contacts the contact member that is deformed can change from the open state to the closed state. .

  In the refrigeration apparatus according to the fourth aspect of the present invention, since the motor can be cooled, heat generation of the motor can be suppressed. Further, it is possible to escape from the surging state by flowing into the suction space through the bypass pipe using the refrigerant for cooling the motor.

The schematic block diagram of the air conditioning apparatus as an example of the freezing apparatus which concerns on this invention. The schematic sectional drawing of a compression mechanism. 1 is a schematic external perspective view of an impeller. The schematic diagram which shows the open state of an opening-and-closing mechanism. The control block diagram of a control part. The schematic block diagram of the air conditioning apparatus as an example of the freezing apparatus which concerns on the modification C.

  Hereinafter, based on drawings, an embodiment of air harmony device 1 as an example of a refrigerating device concerning the present invention is described.

(1) Configuration of Air Conditioner 1 FIG. 1 is a schematic configuration diagram of an air conditioner 1 as an example of a refrigeration apparatus according to the present invention.

  The air conditioner 1 is an apparatus that performs air conditioning of a target space by a vapor compression refrigeration cycle. The air conditioner 1 can perform a cooling operation, and mainly includes a compression mechanism 2, a heat source side heat exchanger 3, a first expansion mechanism 4, and a use side heat exchanger 5. In the present embodiment, HFC-134a is used as the refrigerant, but the present invention is not limited to this.

(1-1) Compression mechanism 2
The compression mechanism 2 is composed of a single-stage centrifugal compressor in which a single compression unit is incorporated. The compression mechanism 2 sucks the low-pressure refrigerant flowing through the suction pipe 6 through the suction port 21, compresses the refrigerant sucked through the suction port 21 into a high-pressure refrigerant, and then passes through the discharge port 22. Discharge to the discharge pipe 7. The suction pipe 6 is a refrigerant pipe that guides the refrigerant from the use side heat exchanger 5 to the suction side (suction port 21) of the compression mechanism 2, and the discharge pipe 7 connects the discharge port 22 from the compression mechanism 2. It is a refrigerant pipe which guides the refrigerant discharged through to the inlet of heat source side heat exchanger 3. The configuration of the compression mechanism 2 will be described in detail later.

(1-2) Heat source side heat exchanger 3
The heat source side heat exchanger 3 functions as a refrigerant radiator that radiates heat of the refrigerant compressed by the compression mechanism 2 by exchanging heat with water or air as a cooling source. One end of the heat source side heat exchanger 3 is connected to the discharge port 22 of the compression mechanism 2 via the discharge pipe 7, and the other end is connected to the first expansion mechanism 4.

(1-3) First expansion mechanism 4
The first expansion mechanism 4 is a mechanism that depressurizes the refrigerant, and an electric expansion valve is used. The first expansion mechanism 4 is configured such that one end is connected to the heat source side heat exchanger 3 and the other end is connected to the use side heat exchanger 5 via the suction pipe 6.

(1-4) Use side heat exchanger 5
The use side heat exchanger 5 functions as a refrigerant heater that heats the refrigerant decompressed by the first expansion mechanism 4 by exchanging heat with water or air as a heating source. The use side heat exchanger 5 is configured such that one end is connected to the first expansion mechanism 4 and the other end is connected to the suction port 21 of the compression mechanism 2.

  The compression mechanism 2, the heat source side heat exchanger 3, the first expansion mechanism 4, and the use side heat exchanger 5 described above are sequentially connected by the refrigerant pipe including the suction pipe 6 and the discharge pipe 7. The main path 11 through which the refrigerant circulates is configured. The main path 11 connects a discharge port 22 of the compression mechanism 2 and a suction space S3, which will be described later, to form a refrigerant path through which the refrigerant discharged from the compression mechanism 2 flows to the suction space S3.

  In the air conditioning apparatus 1 according to the present embodiment, a low-pressure refrigerant is allowed to flow in the motor casing 32 (described later) in order to cool the motor 25 (described later). Therefore, the air conditioner 1 further includes a first bypass pipe 18 and a return pipe 19.

(1-5) First bypass pipe 18
The first bypass pipe 18 guides the refrigerant after being radiated by the heat source side heat exchanger 3 into the motor casing 32 (specifically, the outlet 35 (described later) of the motor casing 32). A refrigerant pipe constituting the path 12 is configured such that one end is connected to the outlet of the heat source side heat exchanger 3 and the other end is connected to the outlet 35 of the motor casing 32. The first bypass pipe 18 is provided with a second expansion mechanism 12a as a pressure reducing mechanism. The second expansion mechanism 12a is an electric expansion valve capable of adjusting the opening degree. By the second expansion mechanism 12a, the high-pressure refrigerant after being radiated by the heat source side heat exchanger 3 is decompressed to a low pressure in the refrigeration cycle.

(1-6) Return pipe 19
The return pipe 19 is a refrigerant pipe that constitutes the return path 13 that guides the low-pressure refrigerant flowing in the motor casing 32 to the use-side heat exchanger 5, and one end thereof is connected to a discharge port 36 (described later) of the motor casing 32. The other end is connected to the inlet of the use side heat exchanger 5.

(2) Detailed Configuration of Compression Mechanism 2 FIG. 2 is a schematic sectional view of the compression mechanism 2. FIG. 3 is a schematic external perspective view of the impeller 41. In the following, the central axis of the rotation shaft 26 as the shaft member is set to OO, and the rotation center of the rotation shaft 26 is set to O. The direction extending along the central axis OO is the axial direction or the front-rear direction (note that the suction side of the compression mechanism 2 is the front), the direction orthogonal to the axial direction is the radial direction, and the direction around the axial direction. Is the circumferential direction.

  The compression mechanism 2 is a so-called oil-less compression mechanism that does not require lubricating oil. As shown in FIG. 2, the compression mechanism 2 mainly includes a compression mechanism casing 23, a compression unit 24, a motor 25, a rotating shaft 26, a radial magnetic bearing 27, a thrust magnetic bearing 28, and a thrust disk 29. The plurality of inlet guide vanes 30 and the second bypass pipe 81 are provided. The compression mechanism 2 includes a hermetic compression mechanism casing 23, a compression unit 24, a motor 25, a rotating shaft 26, a radial magnetic bearing 27, a thrust magnetic bearing 28, a thrust disk 29, and a plurality of inlet guide vanes. 30 is accommodated.

(2-1) Compression mechanism casing 23
The compression mechanism casing 23 is a substantially cylindrical sealed container extending in the axial direction, and includes a compression section casing 31 and a motor casing 32.

(2-1-1) Compression section casing 31
The compression portion casing 31 constitutes an axial front portion (suction side portion) of the compression mechanism casing 23, and the compression portion 24 (to be described later) from the compression space S <b> 1 in which the compression portion 24 is accommodated and the suction port 21 by the inner surface thereof. ) And a suction space S3 through which the suction refrigerant flows.

  The compression section casing 31 is mainly formed with a suction port 21 for sucking refrigerant, a discharge port 22 for discharging refrigerant, and a second bypass pipe through hole 37a. The suction port 21 opens toward one axial end (front end) of the compression mechanism casing 23 and is connected to the suction pipe 6. The discharge port 22 opens toward the radially outer end of the compression mechanism casing 23 and is connected to the discharge pipe 7. The second bypass pipe through-hole 37a is formed so as to extend in the radial direction, and is formed so as to penetrate from the suction space S3 toward the outer surface of the compression mechanism casing 23 (compression section casing 31).

(2-1-2) Motor casing 32
The motor casing 32 is a substantially cylindrical container extending in the axial direction that constitutes the axial rear side portion of the compression mechanism casing 23, and has a substantially cylindrical cylindrical portion 32a having both ends opened in the axial direction, and a cylindrical portion. It has the closure parts 32b and 32c which close the opening of 32a from an axial direction both sides. The motor casing 32 forms a motor housing space S2 for housing the motor 25 by its inner surface.

  The motor casing 32 is mainly formed with an introduction port 35, a discharge port 36, and a second bypass pipe through hole 37b. The introduction port 35 is an opening for introducing the low-pressure liquid refrigerant that has been decompressed by the second expansion mechanism 12a in the first bypass pipe 18 into the motor casing 32 (that is, the motor housing space S2). 1 is connected to the bypass pipe 18. The discharge port 36 is an opening for discharging the refrigerant flowing in the motor casing 32 (motor housing space S2) from the motor casing 32 (motor housing space S2) to the outside (specifically, the return pipe 19). Yes, connected to the return pipe 19. The second bypass pipe through-hole 37b is formed so as to extend in the radial direction, and is formed so as to penetrate from the motor housing space S2 toward the outer surface of the compression mechanism casing 23 (motor casing 32). Thus, by forming the second bypass pipe through holes 37a and 37b, the hollow space S4 of the second bypass pipe 81 is formed so as to communicate with the motor housing space S2 and the suction space S3. .

  The axial rear end surface of the compression portion casing 31 and the axial front end surface of the motor casing 32 (the axial front end surface of the closing portion 32b) function as a partition portion that partitions the compression space S1 and the motor housing space S2. ing.

(2-2) Compression unit 24
The compression unit 24 is a part that compresses the suction refrigerant flowing into the suction space S3 through the suction port 21, and is disposed in the compression space S1. The compressing unit 24 mainly includes an impeller 41 that is provided at one end (specifically, the front end) in the axial direction of the rotating shaft 26 and is rotatable. In the present embodiment, the impeller arrangement space S1a in which the impeller 41 is arranged, the diffuser space S1b located on the radially outer side of the impeller arrangement space S1a, and the scroll space S1c located on the radially outer side of the diffuser space S1b. Collectively, it is called the compression space S1.

  The impeller 41 mainly includes a hub 42 and a plurality of blades 43 and 44 arranged in the circumferential direction so as to protrude in the axial direction from the front surface of the hub 42, and the rotating shaft 26 extending in the front-rear direction of the hub 42. Then, the driving force of the motor 25 is transmitted to rotate about the rotation shaft 26 as an axis. That is, the rotation direction and the circumferential direction of the impeller 41 are the same.

  The hub 42 has a diameter that increases from the front side toward the rear side, and is supported by the rotary shaft 26 so as to rotate integrally with the rotary shaft 26. The hub 42 has a hub front surface 42a which is a circular plane spreading in the radial direction and a hub rear surface 42d which is a circular plane having a larger radius than the hub front surface 42a. ) And the rear face 42d of the hub is arranged to face the rear side.

  The hub 42 further extends from the outer peripheral edge of the hub rear surface 42d in the axial direction, and has a hub cylindrical surface 42b having a common central axis with the hub rear surface 42d, and from the outer peripheral edge of the hub front surface 42a to the front edge of the hub cylindrical surface 42b. And a diameter-expanded curved surface 42c that gently connects so as to be recessed inward in the radial direction. The diameter-expanded curved surface 42c of the impeller 41 is a diameter-expanded curved facing surface that faces the diameter-expanded curved surface 42c and the diameter-expanded curved surface 42c of the impeller-arranged space forming portion that forms the impeller-arranged space S1a of the compression mechanism casing 23. 17 is formed such that the shortest distance between the distance 17 and the distance 17 becomes shorter toward the downstream side in the refrigerant flow direction.

  Large blades 43 and small blades 44 are formed on the enlarged diameter curved surface 42c of the impeller 41 so as to be alternately arranged in the circumferential direction. The large blades 43 and the small blades 44 project so as to be perpendicular to the diameter-expanded curved surface 42c, and the opposed surfaces of the large blades 43 and the small blades 44 are substantially equally spaced in the circumferential direction. It is formed to become.

  Each of the large blades 43 and the small blades 44 constitutes a so-called “rearward blade” by extending spirally so as to be left-handed when viewed from the front. That is, the large blades 43 and the small blades 44 extend so as to turn left while expanding in the radial direction from the hub front surface 42a side toward the hub rear surface 42d side.

  Further, the large blades 43 and the small blades 44 are configured such that the longitudinal direction of the front end portion and the longitudinal direction of the radially outer end portion are in a twisted positional relationship with each other.

  Each large blade 43 is formed so as to extend from the front end portion to the rear end portion of the enlarged diameter curved surface 42c. On the other hand, each small blade 123 is formed to extend from the middle position between the front end portion and the rear end portion of the diameter-expanded curved surface 42c to the rear end portion.

  When the motor 25 is driven, the impeller 41 rotates clockwise (in the direction indicated by the arrow in FIG. 3) in front view, thereby sucking the refrigerant flowing through the suction pipe 6 through the suction port 21, After compression and high pressure, the liquid is discharged toward the discharge pipe 7 through the discharge port 22.

  The front portion of each large blade 43 and small blade 44 and the radially outer portion move along the vicinity of the diameter-enlarged curved facing surface 17 as the impeller 41 rotates. Thereby, the flow rate of the refrigerant can be increased. And the refrigerant | coolant of the state which increased the flow velocity converts kinetic energy into pressure energy in the diffuser space S1b formed in the radial direction outer side (discharge side) of the impeller arrangement space S1a, and becomes a high-pressure refrigerant. The refrigerant having a high pressure in the diffuser space S1b is further decelerated and rectified in the scroll space S1c formed on the radially outer side, and is discharged to the discharge pipe 7 through the discharge port 22.

  As described above, in the compression mechanism 2, by rotating the impeller 41 of the compression unit 24, the refrigerant is sucked from the axial direction, and the sucked refrigerant is caused to flow outward in the radial direction by using the centrifugal force. .

(2-3) Motor 25
The motor 25 is disposed on the rear side of the compression unit 24 and mainly includes a rotor 52 and a stator 53. The motor 25 (the rotor 52 and the stator 53) is accommodated in the motor casing 32 (that is, the motor accommodating space S2) together with the rotating shaft 26, the radial magnetic bearing 27, the thrust magnetic bearing 28, and the thrust disk 29.

  In the present embodiment, as described above, the low-pressure liquid refrigerant that has flowed through the first bypass pipe 18 and depressurized by the second expansion mechanism 12a enters the inlet 35 in the motor casing 32 (motor housing space S2). Is supplied through. The liquid refrigerant flows into the rotary shaft 26 where a cavity is formed. The refrigerant flowing in the rotating shaft 26 is heated by the heat from the motor 25 and evaporates, so that when it goes out of the motor casing 32 from the motor casing 32 through the discharge port 36, it becomes a gas refrigerant. .

(2-3-1) Rotor 52
The rotor 52 is attached to the rotating shaft 26 by being fitted to the rotating shaft 26 connected to the impeller 41 of the compression unit 24. When the rotor 52 rotates, the impeller 41 of the compression unit 24 is driven (rotated) via the rotation shaft 26.

  The rotor 52 mainly has a rotor core 52a and a plurality of magnets (not shown). The rotor core 52a is a substantially cylindrical member in which a rotation shaft is fitted into a central hole, and is formed by stacking electromagnetic steel plates in the axial direction. The plurality of magnets are made of rare earth magnets, for example, and are fitted into the rotor core 52a with a predetermined interval in the circumferential direction.

(2-3-2) Stator 53
The stator 53 is disposed on the outer peripheral side of the rotor 52 and is fixed to the inner peripheral surface of the cylindrical portion 31 of the compression mechanism casing 23 by shrink fitting. The stator 53 mainly has a stator core 53a and windings (not shown) attached to the stator core 53a. The stator 53 is configured such that a rotating magnetic field is generated by energizing each winding. The stator 53 is configured such that its inner peripheral surface forms an air gap t together with the outer peripheral surface of the rotor 52.

(2-4) Radial magnetic bearing 27
The radial magnetic bearing 27 is a bearing that, together with the thrust magnetic bearing 28, rotatably supports the rotary shaft 26 without contact. The radial magnetic bearing 27 supports a load in the radial direction (radial direction) of the rotating shaft 26. In this embodiment, the radial magnetic bearing 27 is arrange | positioned 1 each at the axial direction both ends of the motor 25 so that the motor 25 may be pinched | interposed in an axial direction. That is, in this embodiment, there are two radial magnetic bearings 27.

  Specifically, the radial magnetic bearing 27 mainly has a plurality (four poles in this embodiment) of electromagnets 61 including coils (not shown). The plurality of electromagnets 61 are arranged at predetermined intervals in the circumferential direction on the radially outer side of the rotating shaft 26. That is, the four-pole electromagnet 61 is arranged so that two poles face each other with the rotation shaft 26 in the radial direction. The radial magnetic bearing 27 generates a magnetic field between the plurality of electromagnets 61 and the rotating shaft 26 when a current flows through the coil, and the rotating shaft 26 is magnetically levitated by a magnetic force (magnetic attractive force) generated in the radial direction. By doing so, the rotating shaft 26 is supported in a non-contact manner. That is, the radial magnetic bearing 27 holds the radial position of the rotary shaft 26 by the radial magnetic force generated by the electromagnet 61, that is, constrains the rotary shaft 26 in the radial direction. Thus, since the radial magnetic bearing 27 supports the rotating shaft 26 in a non-contact manner, friction between the rotating shaft and the bearing and wear due to friction can be suppressed.

  In the present embodiment, the radial gap dimension of the radial gap between the rotary shaft 26 and the radial magnetic bearing 27 is detected between the rotary shaft 26 and the radial magnetic bearing 27 (a plurality of electromagnets 61). A radial gap sensor 93 is provided, and the radial gap sensor 93 detects the radial position of the rotary shaft 26. The amount of current flowing through the coil of the radial magnetic bearing 27 and, consequently, the magnetic force is controlled by the radial gap size detected by the radial gap sensor 93, and the radial direction of the rotary shaft 26 is controlled. The position has been determined. The amount of current that flows through the coil of the radial magnetic bearing 27 is controlled by the control unit 9 described later. When the radial gap dimension detected by the radial gap sensor 93 exceeds a predetermined radial gap dimension, the amount of current that is passed through the coil of the radial magnetic bearing 27 by the control unit 9 increases, and the amount of heat generated by the radial magnetic bearing 27 increases. Heat is generated in excess of a predetermined amount.

(2-5) Thrust magnetic bearing 28 and thrust disk 29
The thrust disk 29 is provided at the axial rear end of the rotating shaft 26. The thrust disk 29 is an annular disk member having a flat surface 29 a that extends in the radial direction and faces the axial direction, and a hollow portion thereof is fixed to the rotating shaft 26.

  The thrust magnetic bearings 28 are arranged one by one on both axial sides of the thrust disk 29 so as to face each other in the axial direction with the thrust disk 29 interposed therebetween. The thrust magnetic bearing 28 mainly has an electromagnet 71 including an annular coil (not shown). The thrust magnetic bearing 28 generates a magnetic field between the plurality of electromagnets 71 and the thrust disk 29 when an electric current is passed through the coil, and the thrust disk 29 fixed to the rotating shaft 26 is magnetically generated in the axial direction ( The rotating shaft 26 is supported in a non-contact manner by magnetically levitating with a magnetic attraction force). That is, the thrust magnetic bearing 28 holds the axial position of the rotary shaft 26 and the thrust disk 29 by the axial magnetic force generated by the electromagnet 71, that is, the rotary shaft 26 and the thrust disk 29 are moved in the axial direction. Restrained. The plane 29 a of the thrust disk 29 receives the magnetic force of the thrust magnetic bearing 28. Thus, since the thrust magnetic bearing 28 supports the rotating shaft 26 in a non-contact manner, friction between the rotating shaft and the bearing and wear due to friction can be suppressed.

  In this embodiment, an axial gap sensor 94 that detects an axial gap dimension of an axial gap between the thrust magnetic bearing 28 and the thrust disk 29 between the thrust magnetic bearing 28 and the thrust disk 29. The axial clearance sensor 94 detects the axial position of the thrust disk 29 and, consequently, the rotating shaft 26. The axial gap dimension detected by the axial gap sensor 94 is controlled so that the amount of current flowing through the coil of the thrust shaft air bearing 28 and, consequently, the magnetic force is changed, and the thrust disk 29 and the rotating shaft are controlled. 26 axial positions have been determined. The amount of current that flows through the coil of the thrust magnetic bearing 28 is controlled by the control unit 9. When the axial gap size detected by the axial gap sensor 94 exceeds a predetermined value, the amount of current passed through the coil of the thrust magnetic bearing 28 by the control unit 9 increases, and the amount of heat generated by the thrust magnetic bearing 28 exceeds a predetermined amount. It is supposed to generate heat.

(2-6) Entrance guide vane 30
The plurality of inlet guide vanes 30 are rotatable in the suction space S3 through which the suction refrigerant flows in order to adjust the flow rate and flow direction of the refrigerant (suction refrigerant) sucked by the rotation of the impeller 41 of the compression unit 24. This is a vane member. The plurality of inlet guide vanes 30 are arranged side by side in the circumferential direction, and are driven by a driving device 30a (see FIG. 5, for example, a motor). Note that the drive shaft of the drive device 30a is disposed so as to extend in the radial direction, and the inlet guide vane 30 rotates around an axis extending in the radial direction. And the inclination with respect to the radial direction horizontal surface spread in the radial direction of the inlet guide vane 30 is changed by this rotation. As a result, the flow rate and flow direction of the intake refrigerant described above are adjusted.

(2-7) Second bypass piping 81
In general, centrifugal compressors have the advantage of being able to suck in and compress a large amount of refrigerant. On the other hand, if the amount of refrigerant sucked falls below a predetermined amount, the phenomenon of fluctuations in discharge pressure and flow rate, called surging, occurs. There is a problem that the vibration of the machine becomes large.

  Therefore, in this embodiment, the second bypass pipe 81 is provided to escape from the surging state. The second bypass pipe 81 is a refrigerant pipe that guides the low-pressure gas refrigerant evaporated by heat from the motor 25 in the motor casing 32 (motor housing space S2) to the suction space S3 of the compression mechanism 2, and has one end. Is connected to the motor housing space S2 through the second bypass pipe through-hole 37b, and the other end is connected to the suction space S3 of the compression mechanism 2 through the second bypass pipe through-hole 37a. . An opening / closing mechanism 82 is provided in the vicinity of one end of the second bypass pipe 81 that contacts the motor housing space S2. The opening / closing mechanism 82 is opened / closed to permit / block the low-pressure gas refrigerant flowing through the motor casing 32 (motor housing space S2) from flowing into the suction space S3. The detailed configuration of the opening / closing mechanism 82 will be described later. The second bypass pipe 81 allows only a refrigerant flow from the motor casing 32 (motor housing space S2) to the suction space S3, and the refrigerant from the suction space S3 to the motor casing 32 (motor housing space S2). A check mechanism (not shown, for example, a check valve) for blocking the flow is provided.

  The second bypass pipe 81 forms a second bypass path 14 that guides the low-pressure gas refrigerant flowing in the motor casing 32 (motor housing space S2) to the suction space S3 of the compression mechanism 2. And in the air conditioning apparatus 1 of this embodiment, the refrigerant circuit 10 (refer FIG. 1) through which a refrigerant | coolant flows with the main path | route 11, the 1st bypass path | route 12, the return path | route 13, and the 2nd bypass path | route 14 is shown. Is formed.

(3) Opening / closing mechanism 82
FIG. 4 is a schematic diagram showing an open state of the opening / closing mechanism 82.

  The opening / closing mechanism 82 is provided in the vicinity of one end of the second bypass pipe 81 that contacts the motor housing space S2, and is switched between an open state (see FIG. 4) and a closed state (see FIG. 1). 2 is a mechanism for opening and closing the bypass pipe 81. The open state is a state in which a low-pressure gas refrigerant flowing through the motor casing 32 (motor housing space S2) flows into the suction space S3. That is, in the open state, the motor casing 32 (motor housing space S2) and the suction space S3 are in communication with each other via the second bypass pipe 81 (hollow space S4). The closed state is a state where the low-pressure gas refrigerant flowing through the motor casing 32 (motor housing space S2) is blocked from flowing into the suction space S3. That is, in the closed state, the inside of the motor casing 32 (motor housing space S2) and the hollow space S4 of the second bypass pipe 81 are not in communication. The opening / closing mechanism 82 functions as a surging escape mechanism that escapes from the surging state by changing from the closed state to the open state when entering the surging state. A specific configuration will be described. The opening / closing mechanism 82 includes an opening / closing member 83 for opening / closing the second bypass pipe 81 and a driving member 84 for driving the opening / closing member 83.

(3-1) Opening / closing member 83
The opening / closing member 83 includes a valve 83a that directly opens and closes the second bypass pipe 81, and a support member 83b that supports the valve 83a.

  The valve 83 a is configured to be movable from the radially inner side to the radially outer side by the driving member 84, and is in contact with the inner surface of the second bypass pipe 81 and does not contact the inner surface of the second bypass pipe 81. Switch between non-contact state. The open / close state of the open / close mechanism 82 is switched by switching the valve 83a between a contact state and a non-contact state.

  The support member 83 b is a rod-like member extending in the radial direction, one end surface of which is fixed to a surface facing the rotation shaft 26 of the valve 83 a and the other end surface of which is fixed to the drive member 84. The support member 83b supports the valve 83a by being fixed to the drive member 84.

(3-2) Drive member 84
The drive member 84 is a U-shaped plate-shaped member that opens toward the front end in the axial direction, and contacts the radial magnetic bearing 27 (electromagnet 61) so that the radial magnetic bearing 27 (electromagnet 61) is disposed in the opening. Are arranged. One end of the drive member 84 is fixed to the compression mechanism casing 23 (specifically, the rear end surface in the axial direction of the closing portion 32b of the motor casing 32), and the other end is a free end. In FIG. 2, the drive member 84 is drawn to overlap the rotary shaft 26, but the drive member 84 does not enter the rotary shaft 26.

  The drive member 84 is made of a bimetal having a two-layer structure, and has a first thermal expansion coefficient plate 84a and a second thermal expansion coefficient plate 84b. The first thermal expansion coefficient plate 84a is made of a metal having a higher thermal expansion coefficient than the second thermal expansion coefficient plate 84b, and constitutes an inner part of the drive member 84, that is, a part that contacts the radial magnetic bearing 27. ing. The second coefficient of thermal expansion 84b is made of a metal having a lower coefficient of thermal expansion than the first coefficient of thermal expansion 84a, and constitutes the outer portion of the drive member 84. Since the drive member 84 has such a configuration, the deformation due to the difference in thermal expansion coefficient between the first thermal expansion coefficient plate 84a and the second thermal expansion coefficient plate 84b is changed according to the temperature change. Arise. Specifically, when the temperature rises, the expansion amount of the first coefficient of thermal expansion plate 84a is larger than the expansion amount of the second coefficient of thermal expansion plate 84b, so that the drive member 84 is deformed so as to spread outward. become.

  Note that the support member 83b of the opening / closing member 83 is not fixed to the portion of the drive member 84 located on the side close to the second bypass pipe 81, and only the portion of the drive member 84 located on the side far from the second bypass pipe 81. It is fixed to. Therefore, when the drive member 84 is deformed outward as the temperature changes (temperature rise), the opening / closing member 83 fixed to the portion of the drive member 84 located on the far side from the second bypass pipe 81 is the second bypass pipe 81. It moves toward only the direction away from (see FIG. 4).

  As described above, the drive member 84 is a temperature deformation member that is formed of a bimetal having a two-layer structure and deforms due to a temperature change. Therefore, in this embodiment, since the opening / closing member 83 is connected to the driving member 84 that is such a temperature deforming member, the contact state and the non-contact state of the valve 83a can be switched. Thus, the second bypass pipe 81 can be opened and closed.

  Here, a temperature change (temperature increase) that causes the drive member 84 to deform generally occurs when a surging state is entered. Specifically, when surging occurs, the compression mechanism 2 vibrates, and the radial gap dimension detected by the radial gap sensor 93 increases. For this reason, a state occurs in which the radial gap dimension exceeds the predetermined radial gap dimension (predetermined value). The predetermined radial clearance dimension is a radial clearance dimension between the rotary shaft 26 and the radial magnetic bearing 27, which is set by calculation in advance by simulation, desktop calculation, or the like. When the radial gap dimension detected by the radial gap sensor 93 exceeds a predetermined radial gap dimension, the control unit 9 determines the amount of current flowing through the coil of the radial magnetic bearing 27 in order to suppress the vibration of the compression mechanism 2. Will increase. As described above, when the surging state is entered, the time during which a large amount of current flows through the radial magnetic bearing 27 becomes longer, so the amount of heat generated by the radial magnetic bearing 27 increases. As a result, a temperature change (temperature increase) occurs such that the drive member 84 is deformed.

  As described above, in this embodiment, when the surging state is entered, the amount of heat generated by the radial magnetic bearing 27 exceeds a predetermined amount, so that the temperature around the drive member 84 naturally deforms the drive member 84. Temperature. Then, the support member 83 b of the opening / closing member 83 fixed to the drive member 84 moves in a direction away from the second bypass pipe 81 with the deformation corresponding to the temperature change (temperature increase) of the drive member 84. As the support member 83b of the opening / closing member 83 moves, the valve 83a of the opening / closing member 83 fixed to the support member 83b also moves in a direction away from the second bypass pipe 81 and enters a non-contact state. As a result, the opening / closing mechanism 82 is opened, and the second bypass pipe 81 is opened.

  When the low-pressure gas refrigerant flowing through the motor housing space S2 is flowed into the suction space S3 and the flow rate of the suction refrigerant sucked by the compression unit 24 exceeds a predetermined amount, the surging state is escaped. When the surging state is escaped, the drive member 84 is deformed according to the temperature change (temperature decrease) and returns to the original state. The opening / closing mechanism 82 also returns to its original state with the deformation of the driving member 84 according to the temperature change. That is, the valve 83a of the opening / closing member 83 is in a contact state, and the opening / closing mechanism 82 is in a closed state.

(4) Configuration of Control Unit 9 FIG. 5 is a control block diagram of the control unit 9.

  As described above, the air conditioner 1 includes the air conditioner 1 such as the first expansion mechanism 4, the second expansion mechanism 12 a, the motor 25, the radial magnetic bearing 27, the thrust magnetic bearing 28, and the drive device for the inlet guide vane 30. It further has a control unit 9 that controls the operation of each component. The control unit 9 includes a CPU, a RAM, a ROM, and the like, and is connected to the radial gap sensor 93, the axial gap sensor 94, the flow rate sensor 95 that detects the flow rate of the refrigerant flowing through the suction space S3, and the like. Yes. And the operation | movement of each above-mentioned element is controlled in response to the detection result from these sensors.

(5) Features (5-1)
In the air conditioner 1 of the present embodiment, first, the refrigerant is supplied from the main path 11 through the first bypass path 12 into the motor casing 32 (motor housing space S2). Further, in the present embodiment, the second bypass pipe 81 connecting the inside of the motor casing 32 (motor housing space S2) and the suction space S3 to the compression mechanism 2, and when surging occurs, that is, the radial magnetic bearing 27 An opening / closing mechanism 82 that changes from a closed state to an open state when the amount of generated heat exceeds a predetermined amount is provided. The opening / closing mechanism 82 includes an opening / closing member 83 having a valve 83a and a support member 83b, and a drive member 84. The drive member 84 is a temperature deformation member that is deformed by a temperature change. Specifically, a bimetal composed of two metal plates 84a and 84b having different coefficients of thermal expansion is used. Then, the drive member 84 as a contact member that contacts the radial magnetic bearing 27 is deformed when the heat generation amount of the radial magnetic bearing 27 exceeds a predetermined amount, so that the support member 83b fixed to the drive member 84 is interposed. The valve 83a moves in a direction away from the second bypass pipe 81 (takes a non-contact state). As a result, the second bypass pipe 81 is opened.

  In the present embodiment, since the compression mechanism 2 has such a configuration, the second bypass pipe 81 is opened when surging occurs. When the second bypass pipe 81 is opened, the refrigerant flowing in the motor casing 32 (motor housing space S2) is guided to the suction space S3. Thereby, the refrigerant | coolant which flows in into the compression part 24 of the compression mechanism 2 can be increased. As described above, the air conditioner 1 of the present embodiment has the compression mechanism 2 that can escape from the surging state with a simple configuration.

  When surging occurs, the compression mechanism 2 vibrates, so the radial gap dimension detected by the radial gap sensor 93 may exceed a predetermined radial gap dimension (predetermined value). When the radial gap dimension exceeds the predetermined radial gap dimension, the amount of current that is passed through the coil of the radial magnetic bearing 27 by the control unit 9 is increased in order to suppress vibration of the compression mechanism 2. That is, when surging occurs, the amount of current flowing through the coil of the radial magnetic bearing 27 is increased, and the amount of heat generated by the radial magnetic bearing 27 is increased to exceed a predetermined amount.

  Thus, in the present embodiment, driving as a temperature deforming member around the radial magnetic bearing 27 that generates heat so that the phenomenon that the amount of heat generated by the radial magnetic bearing 27 exceeds a predetermined amount when surging occurs can be used. A member 84 is disposed. Then, the opening / closing member 83 is configured to open and close the second bypass pipe 81 using the deformation accompanying the temperature change of the drive member 84.

(5-2)
In the present embodiment, the refrigerant from the heat source side heat exchanger 3 is supplied to the motor casing 32 (motor housing space S2) by the second expansion mechanism 12a with a reduced pressure. Thereby, the motor 25 can be cooled and the heat generation of the motor 25 can be suppressed. Moreover, it can escape from a surging state by making it flow into suction space S3 through the 2nd bypass piping 81 using the refrigerant | coolant which cools the motor 25. FIG.

(6) Modifications The embodiment of the present invention has been described above with reference to the drawings. However, the specific configuration is not limited to the above-described embodiment, and can be changed without departing from the gist of the invention. .

(6-1) Modification A
In the embodiment described above, the opening / closing mechanism 82 has been described as having the opening / closing member 83 and the driving member 84, but is not limited thereto.

  For example, the opening / closing mechanism 82 may be configured by a valve 83 a that constitutes the opening / closing member 83. At this time, the valve 83a is preferably composed of the above-described bimetal, and is preferably disposed at a position in contact with the radial magnetic bearing 27 or a position in the vicinity of the radial magnetic bearing 27. Thus, when the amount of heat generated by the radial magnetic bearing 27 exceeds a predetermined amount (that is, when surging occurs), the valve 83a can be deformed to change from the closed state to the open state. Therefore, it is possible to obtain the same effect as the above embodiment.

(6-2) Modification B
Although the said embodiment demonstrated that the compression mechanism 2 was comprised from the single stage type centrifugal compressor in which the single compression part was integrated, it is not restricted to this. For example, a compression mechanism having one uniaxial two-stage compression structure may be used, or a multi-stage compression mechanism may be used as compared with a two-stage compression type such as a three-stage compression type. A parallel multi-stage compression type compression mechanism in which two or more compressors are connected in parallel may be used.

(6-3) Modification C
FIG. 6 is a schematic configuration diagram of an air-conditioning apparatus 100 according to Modification C.

  In the above embodiment, the refrigerant supplied into the motor casing 32 (motor housing space S2) has been described as a low-pressure refrigerant that is radiated by the heat source side heat exchanger 3 and decompressed by the second expansion mechanism 12a. However, it is not limited to this.

  For example, the low-pressure refrigerant heated and evaporated by the use-side heat exchanger 5 is radiated by the heat source-side heat exchanger 3 and is decompressed by the second expansion mechanism 12a together with the low-pressure refrigerant in the motor casing 32 (motor It may be supplied to the accommodation space S2).

  In this case, as shown in FIG. 6, the air conditioning apparatus 1 has an introduction bypass pipe having one end connected to the outlet of the use side heat exchanger 5 and the other end connected to the inside of the motor casing 32 (motor housing space S <b> 2). 16 is provided. The introduction bypass pipe 16 constitutes an introduction bypass path 15 that guides the refrigerant evaporated in the use side heat exchanger 5 into the motor casing 32 (motor housing space S2). The introduction bypass path 15 forms the refrigerant circuit 101 through which the refrigerant flows together with the main path 11, the first bypass path 12, the return path 13, and the second bypass path 14. In the case of this modification, the cooling effect of the motor 25 can be further enhanced.

(6-4) Modification D
In the above embodiment, the air conditioner 1 capable of performing the cooling operation has been described as an example of the refrigeration apparatus. However, the present invention is not limited to this, and the present invention can switch between the cooling operation and the heating operation. You may apply to an air conditioning apparatus and may apply to a heat pump type hot-water supply apparatus.

  The present invention can be variously applied to a refrigeration apparatus having a compression mechanism employing a magnetic bearing.

1 Air conditioning equipment (refrigeration equipment)
3 Heat source side heat exchanger (heatsink)
9 Control unit 22 Discharge port 24 Compression unit 25 Motor 26 Rotating shaft 27 Radial magnetic bearing (magnetic bearing)
32 Motor casing 61 Electromagnet 81 Second bypass piping (bypass piping)
82 Opening / closing mechanism 83 Opening / closing member 84 Contact member 93 Radial gap sensor (gap sensor)
S3 Suction space

JP-A-6-346893

Claims (4)

A compression mechanism (2) for discharging the refrigerant flowing through the suction space (S3) to the outside through the discharge port (22) after being compressed;
A refrigerant path connecting the discharge port and the suction space and allowing the refrigerant discharged from the compression mechanism to flow to the suction space;
With
The compression mechanism is
A compression section (24) for compressing the refrigerant;
A motor (25) attached to a rotary shaft (26) connected to the compression unit and driving the compression unit via the rotary shaft;
A magnetic bearing (27) for rotatably supporting the rotating shaft without contact;
A motor casing (32) that houses the motor and the magnetic bearing and is supplied with refrigerant flowing through the refrigerant path;
A bypass pipe (81) for flowing the refrigerant in the motor casing to the suction space;
The bypass bearing is opened and closed by switching between an open state in which the refrigerant in the motor casing flows into the suction space and a closed state in which the refrigerant in the motor casing is blocked from flowing into the suction space, and heat generation of the magnetic bearing An opening and closing mechanism (82) that changes from the closed state to the open state when the amount exceeds a predetermined amount;
A refrigeration apparatus (1) having The magnetic bearing has an electromagnet (61) including a coil,
A control unit (9) for controlling the amount of current flowing to the coil,
The compression mechanism further includes a gap sensor (93) for detecting a gap size of a gap between the rotating shaft and the magnetic bearing,
The control unit increases the amount of current flowing through the coil when a gap size detected by the gap sensor exceeds a predetermined value.
The refrigeration apparatus according to claim 1. The opening / closing mechanism includes an opening / closing member (83) for opening / closing the bypass pipe, and a contact member (84) for contacting the opening / closing member and the magnetic bearing,
The contact member is a temperature deformation member that deforms due to a temperature change,
The opening and closing member changes from the open state to the closed state by deforming the contact member when the amount of heat generated by the magnetic bearing exceeds a predetermined amount.
The refrigeration apparatus according to claim 1 or 2. A heat radiator (3) provided in the refrigerant path for radiating the refrigerant,
The refrigerant that has passed through the radiator is decompressed and supplied into the motor casing.
The refrigeration apparatus of any one of Claims 1-3.

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