JP7035201B2 - Compressor and air conditioner using it - Google Patents

Description

The present invention relates to a compressor and an air conditioner using the compressor.

As the refrigerant used in refrigerators, air conditioners, refrigerators and the like, for example, R134a, R410A, R407C and the like are used. Although these refrigerants have little effect on the ozone layer, they have a large global warming potential (GWP). As an alternative refrigerant, for example, trifluoroiodomethane (CF3I) has been proposed. The GWP of trifluoroiodomethane (CF3I) is 0.4, which is smaller than that of GWP2090 of R410A. As such a technique, there are, for example, Patent Document 1 and Patent Document 2.

Patent Document 1 discloses a technique using trifluoroiodomethane (CF3I) as a refrigerant and bisphenols as an additive for refrigerating machine oil.

Further, Patent Document 2 discloses a technique in which a refrigerant mixed with trifluoroiodomethane (CF3I) is used as a refrigerant and an organic coating film or an inorganic coating film is applied to a sliding portion of a compressor.

Japanese Unexamined Patent Publication No. 2009-235111 WO2009 / 0662727

Trifluoroiodomethane (CF3I) has a global warming potential about one-third that of R410A, but has a higher discharge temperature in compressors than R134a, R410A, R407C, etc., and is used in electric motors. There is a risk of demagnetizing the permanent magnets.

Patent Document 1 and Patent Document 2 disclose that trifluoroiodomethane (CF3I) is used as a refrigerant, but all consideration is given to suppressing demagnetization of permanent magnets caused by an increase in discharge temperature. I wasn't. Therefore, in Patent Document 1 and Patent Document 2, it is a factor that causes a deterioration in the performance of the compressor.

An object of the present invention is to solve the above-mentioned problems and to provide a compressor using trifluoroiodomethane (CF3I) as a refrigerant and suppressing performance deterioration due to demagnetization of a permanent magnet, and an air conditioner using the compressor. It is in.

In order to achieve the above object, the present invention includes a high-pressure chamber type closed container, a compression mechanism housed in the closed container to compress the refrigerant, and an electric motor for driving the compression mechanism. , A compressor equipped with a stator having a coil and a rotor having a permanent magnet, wherein the refrigerant is trifluoroiodomethane (CF3I) alone, or the trifluoroiodomethane (CF3I) and another refrigerant. It is a mixed refrigerant containing, and the material of the permanent magnet is formed by containing a rare earth element in an Nd-Fe-B system magnet, and the rare earth element is concentrated in the vicinity of the grain boundary of the Nd-Fe-B system magnet. A temperature sensor for distributing and detecting the discharge temperature of the refrigerant discharged from the compression mechanism and a control means for controlling the electric motor are provided, and the control means is based on a signal from the temperature sensor. The purpose is to control the current supplied to the electric motor so that the current flowing through the motor is equal to or less than the 1% demagnetization start current of the permanent magnet at the discharge temperature of the refrigerant.

According to the present invention, it is possible to provide a compressor using trifluoroiodomethane (CF3I) as a refrigerant and suppressing performance deterioration due to demagnetization of a permanent magnet, and an air conditioner using the compressor.

It is a vertical sectional view of the closed type electric compressor which concerns on embodiment of this invention. It is a perspective view of the rotor in the electric motor of a closed type electric compressor. It is a figure which looked at the permanent magnet in the rotor 7a from the axial direction. FIG. 3B is a cross-sectional view taken along the line IIIB-IIIB of FIG. 3A. It is a partially enlarged view which shows the vicinity of the magnet accommodating part for one pole in a rotor 7a. It is a metal distribution map in the matrix grain of the Nd-Fe-B compound which constitutes a permanent magnet in this Example. It is a control circuit diagram of the closed type electric compressor which concerns on embodiment of this invention. It is a cycle block diagram of the air conditioner which concerns on embodiment of this invention.

Hereinafter, examples of a closed electric compressor according to the present invention and an air conditioner using the same will be described with reference to the drawings. The present invention is not limited to the following examples, and various modifications and applications are included in the technical concept of the present invention.

FIG. 1 is a vertical sectional view of a closed electric compressor 50 according to an embodiment of the present invention. The sealed electric compressor 50 (compressor) is used as a component of a refrigerating cycle such as a refrigerating and air-conditioning device (for example, an air conditioner, a refrigerator, a freezer, a refrigerator / freezing showcase, etc.) and a heat pump type hot water supply device. As shown in FIG. 1, the closed electric compressor 50 includes a closed container 1, a compression mechanism 2, and an electric motor 7 as main components.

The closed container 1 has a cylindrical tubular portion 1a, a lid portion 1b welded to the top and bottom of the tubular portion 1a, and a bottom portion 1c, and the inside is a closed space. In this embodiment, a high-pressure chamber type closed container 1 is used.

The closed container 1 houses the compression mechanism 2 and the electric motor 7, and stores the lubricating oil 8 such as an ether compound and an ester compound in the bottom 1c. The oil level of the lubricating oil 8 is set to be located above the auxiliary bearing 15.

The closed container 1 is provided with a suction pipe 11 penetrating the lid portion 1b and a discharge pipe 22 penetrating the tubular portion 1a. The discharge pipe 22 is located directly below the frame 5 and projects toward the center of the closed container 1. The tip of the discharge pipe 22 extends toward the center from the outer peripheral surface of the coil end 17 and opens.

The compression mechanism 2 of this embodiment compresses trifluoroiodomethane (CF3I) alone or a mixed refrigerant (mixed refrigerant gas) containing trifluoroiodomethane (CF3I) and another refrigerant and discharges it into the closed container 1. It is a thing and is arranged in the upper part in the closed container 1. The compression mechanism 2 includes a fixed scroll 3, a swivel scroll 4, a frame 5, and an old dam ring 10 as main components.

The fixed scroll 3 has a spiral wrap on the end plate and is bolted onto the frame 5. A suction port 12 is provided at the peripheral edge of the fixed scroll 3, and a discharge port 14 is provided at the center. A suction pipe 11 communicates with the suction port 12. The discharge port 14 communicates with the space above the compression mechanism 2 in the closed container 1.

The swivel scroll 4 has a spiral wrap on the end plate. The swivel scroll 4 is sandwiched between the fixed scroll 3 and the frame 5. The lap of the swivel scroll 4 and the lap of the fixed scroll 3 are meshed with each other to form a compression chamber.

On the non-fixed scroll side of the swivel scroll 4, a boss portion in which a swivel bearing is incorporated is provided. An eccentric pin portion 6a that drives the swivel scroll 4 eccentrically is fitted in this swivel bearing.

The old dam ring 10 constitutes a rotation regulation mechanism of the turning scroll 4. The old dam ring 10 is installed between the swivel scroll 4 and the frame 5, and prevents the revolving swivel scroll 4 from rotating to perform a circular orbital motion.

The frame 5 in this embodiment is fixed to the closed container 1 by welding. The frame 5 supports a fixed scroll 3, an old dam ring 10, and a swivel scroll 4. In the center of the frame 5, a tubular portion protruding downward is provided. A main bearing 5a that pivotally supports the shaft 6 is provided in the tubular portion.

A plurality of discharge gas passages 18a that communicate the upper space of the fixed scroll 3 and the lower space of the frame 5 are formed on the outer peripheral portion of the fixed scroll 3 and the frame 5.

The electric motor 7 includes a rotor 7a, a stator 7b, a shaft 6, and a balance weight 16 as main components. The rotor 7a will be described in detail later.

The stator 7b includes a coil 24 having a plurality of conductors through which an electric current is passed to generate a rotating magnetic field, and an iron core 23 for efficiently transmitting the rotating magnetic field as main components.

The coil 24 of the stator 7b in this embodiment is wound by a centralized winding method.

The iron core 23 is shrink-fitted into the closed container 1 and fixed by welding or the like. A large number of notches are formed on the outer circumference of the stator 7b over the entire circumference, and a discharge gas passage 18b is formed between the notches and the closed container 1.

The shaft 6 is fitted in the central hole of the rotor 7a and integrated with the rotor 7a. One side (upper side in the illustrated example) of the shaft 6 protrudes from the rotor 7a and is engaged with the compression mechanism 2, and an eccentric force is applied by the compression operation of the compression mechanism 2. In this embodiment, both sides (upper and lower in the drawing) of the shaft 6 are projected from both sides of the rotor 7a, and the shaft 6 is pivotally supported by the main bearing 5a and the sub-bearing 15 on both sides of the rotor 7a and rotates stably. be able to. The auxiliary bearing 15 is supported by a support member welded and fixed to the closed container 1 and is immersed in the lubricating oil 8.

The lower end of the shaft 6 extends into the oil reservoir 9 at the bottom of the closed container 1. The shaft 6 is provided with a through hole 6b for supplying the lubricating oil 8 to each bearing portion and each sliding surface so that the lubricating oil 8 can be sucked up from the through hole 6b from the oil reservoir 9 at the lower end portion. The lubricating oil 8 sucked up from the oil reservoir 9 through the shaft through hole in the compression mechanism 2 is supplied to each bearing and the sliding portion of the compression mechanism 2. The lubricating oil 8 supplied to the sliding portion of the compression mechanism 2 is discharged together with the refrigerant gas from the discharge port 14 at the center of the fixed scroll 3.

The balance weight 16 is composed of an upper balance weight (compression mechanism side balance weight) 16a and a lower balance weight (anti-compression mechanism side balance weight) 16b installed on both sides (upper and lower in the drawing) of the rotor 7a, and is composed of a plurality of balance weights 16. It is fixed to the rotor 7a by the rivet 30.

In the sealed electric compressor 50 as described above, when the electric motor 7 is energized and the rotor 7a rotates, the shaft 6 rotates. As a result, the eccentric pin portion 6a performs an eccentric rotational motion, and the swivel scroll 4 swivels. The compression chamber formed between the fixed scroll 3 and the swivel scroll 4 becomes smaller while moving from the outer peripheral side to the central portion. The refrigerant gas sucked through the suction pipe 11 and the suction port 12 is compressed in the compression chamber. The compressed refrigerant gas is discharged from the discharge port 14 at the center of the fixed scroll 3 into the upper space (discharge pressure space) in the closed container 1 and discharged to the outside of the closed container 1 via the discharge pipe 22.

Next, the rotor 7a according to the embodiment of the present invention will be described in more detail. FIG. 2 is a perspective view of a rotor in an electric motor of a closed electric compressor according to an embodiment of the present invention. In addition, in FIG. 2, the upper balance weight 16a and the lower balance weight 16b are shown together. Further, in FIG. 2, the upper balance weight 16a and the rotor 7a are partially broken for convenience of drawing.

As shown in FIG. 2, the rotor 7a includes an iron core 25 and a permanent magnet 33 built in the iron core 25 as main components. The rotor 7a converts the rotating magnetic field from the stator 7b into a rotary motion, and rotates around the shaft 6 (see FIG. 1). The rotor 7a is rotatably arranged in the central hole of the iron core 23 (see FIG. 1) of the stator 7b (see FIG. 1).

The rotor 7a includes permanent magnets 33 inserted into a plurality of magnet accommodating portions 31. The permanent magnet 33 is formed of a thin rectangular parallelepiped. In the permanent magnet 33, the area of the surface indicated by the reference numeral B in the magnetization direction is larger than the area of the surface indicated by the reference numeral A. Of the six surfaces of the permanent magnet 33, the widest two surfaces (pair of B surfaces) are arranged so as to face the centrifugal direction of the rotor 7a. The lower surface of the rotor 7a is closed by a lower balance weight 16b or the like. As a result, the permanent magnet 33 is held so as not to come out from the lower surface of the magnet accommodating portion 31.

3A and 3B are layouts of the permanent magnets 33 in the rotor 7a, FIG. 3A is a view seen from the axial direction, and FIG. 3B is a cross-sectional view taken along the line IIIB-IIIB of FIG. 3A.

As shown in FIG. 3A, the permanent magnets 33 inserted in each magnet accommodating portion 31 are composed of a plurality of permanent magnets 33. In this embodiment, the permanent magnets 33 are divided into three and arranged in each of the four magnet accommodating portions 31. An eddy current is generated in the permanent magnet 33 due to the influence of the magnetic field from the stator 7b, but the eddy current loss is reduced by dividing the permanent magnet 33.

The rotor 7a has a pole portion 51 in which a permanent magnet is embedded, and an interpole portion 52 located between the pole portions 51. In the rotor 7a in this embodiment, the radial length X in the interpole portion 52 is shorter than the radial length Y in the pole portion 51. According to such a rotor 7a, the iron core 25 through which the magnetic flux passes can be narrowed, and the leakage flux of the permanent magnet 33 can be reduced.

As shown in FIG. 3B, a gap R is formed between the upper end portion of the magnet accommodating portion 31 in the axial direction and the permanent magnet 33. By providing such a gap R, it is possible to cope with a dimensional error when arranging the permanent magnet 33 in the magnet accommodating portion 31. Further, as will be described later, this gap R is set to be larger than the gap Q (see FIG. 4) with the magnet accommodating portion 31 in the magnetization direction of the permanent magnet 33.

The iron core 25 has a planar shape shown in FIG. 3A, for example, silicon steel plates are formed by being laminated in the axial direction as shown in FIG. 3B.

FIG. 4 is a partially enlarged view showing the vicinity of the magnet accommodating portion 31 for one pole in the rotor 7a. When medium-heavy rare earth elements such as Dy and Tb are unevenly distributed near the grain boundaries of Nd-Fe-B-based sintered magnets as permanent magnet materials, slip deformation is restricted by dispersion strengthening. Therefore, the permanent magnet becomes stronger against the moment, but becomes more brittle.

Since the permanent magnet 33 in this embodiment has a large magnetic force, it is difficult to think that the permanent magnet 33 moves in the magnet accommodating portion 31. Here, for the sake of completeness, it is assumed that the permanent magnet 33 is subjected to the inertial force and the centrifugal force accompanying the acceleration and deceleration of the rotor 7a, and the permanent magnet 33 divided into three pieces moves in the magnet accommodating portion 31. ..

As described above, the magnet accommodating portion 31 accommodates the permanent magnet 33 by providing a gap R (see FIG. 3B) in the axial direction. In addition to this gap R, as shown in FIG. 4, the magnet accommodating portion 31 has a gap Q formed between the permanent magnet 33 and the magnet accommodating portion 31 in the magnetization direction of the permanent magnet 33. By providing such a gap Q, the dimensional error when arranging the permanent magnet 33 in the magnet accommodating portion 31 is absorbed.

Further, the gap Q is formed so as to be narrower than the above-mentioned gap R (see FIG. 3B). In the rotor 7a (see FIG. 2) in this embodiment, since the gap Q is narrower than the gap R, the three permanent magnets 33 are prevented from moving in the magnetization direction. That is, when the adjacent permanent magnets 33 move in the magnetization direction, they come into contact with each other at an angle, so that the corner portions of the permanent magnets 33 do not collide with each other. Further, since the gap R (see FIG. 3B) is larger than the gap Q, the three permanent magnets 33 are preferentially displaced in the axial direction rather than moving in the magnetization direction, so that the corners of the permanent magnet 33 are displaced. It prevents them from colliding with each other. Therefore, according to the rotor 7a (see FIG. 2), it is possible to prevent grain boundary cracking from occurring at the corners of the permanent magnet 33.

It is desirable that the gap Q in this embodiment is set so as not to be too wide, and such a gap Q having a predetermined width has a good magnetic force between the permanent magnet 33 and the iron core 25 in the magnetization direction. maintain. Incidentally, the gap Q in this embodiment is assumed to be about 0.1 mm, but is not limited to this.

Next, the permanent magnet 33 of this embodiment will be described in more detail. The permanent magnet 33 (see FIG. 2) of the rotor 7a (see FIG. 2) in this embodiment has a magnetizing rate of 98.5% or more. The permanent magnet 33 is obtained by externally magnetizing the Nd-Fe-B compound described below. In this embodiment, a neodymium magnet having an intrinsic coercive force of 800 kA / m or more is used as the permanent magnet.

FIG. 5 is a metal distribution diagram in the matrix grain of the Nd—Fe—B compound constituting the permanent magnet 33 in this embodiment. The permanent magnet 33 in this embodiment contains the alloy represented by the composition formula of Nd2Fe14B as a main component. More specifically, as shown in FIG. 5, the permanent magnet 33 has the medium-heavy rare earth element 37 described later distributed so as to surround the crystal particles 34 made of the Nd2Fe14B alloy. In other words, the Nd-Fe-B compound constituting the permanent magnet 33 is a medium-heavy rare earth element 37 described later diffusely distributed in the vicinity of the grain boundary 35 of the crystal particles 34 made of the Nd2Fe14B alloy.

Examples of the medium-heavy rare earth element 37 include Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Eu, Y, Sc and the like. Above all, it is desirable to use Tb and Dy. Such an Nd-Fe-B compound is obtained by mixing an alloy 36 rich in a medium-heavy rare earth element 37 at the time of magnet sintering.

Examples of the alloy 36 include, but are not limited to, Tb-Fe, Dy-Al, Tb4O7, Dy2O3 and the like.

In the permanent magnet 33 made of the Nd-Fe-B compound, the magnitude of the external magnetic field generated by the nucleus of the reverse magnetic domain on the surface of the grain boundaries 35 is the coercive force. The structure of the surface of the grain boundary 35 has a strong influence on the nucleation of the reverse magnetic domain, and the disorder of the crystal structure in the vicinity of the grain boundary 35 causes the disorder of the magnetic structure and promotes the formation of the reverse magnetic domain. It is considered that the magnetic structure from the crystal interface to a depth of about 5 nm contributes to the promotion of the formation of reverse magnetic domains.

In this embodiment, as described above, the medium-heavy rare earth element 37 is intensively distributed in the vicinity of the grain boundaries 35. As a result, the permanent magnet 33 of this embodiment can increase the holding power as compared with the permanent magnet 33 in which the medium-heavy rare earth element 37 is uniformly distributed in the Nd2Fe14B alloy. Here, the vicinity of the grain boundary 35 means the surface layer of the matrix grain from the crystal interface (grain boundary 35) to a depth of about 5 nm among the matrix grains.

Therefore, the ratio of the medium-heavy rare earth element 37 to Nd, which is a constituent of the Nd-Fe-B compound, in the vicinity of the grain boundary 35, and the ratio of the medium-heavy rare earth element 37 to Nd in the matrix grains inside the vicinity of the grain boundary 35. By making it larger than the above, the coercive force of the permanent magnet 33 can be increased.

Further, in the Nd-Fe-B compound of this example, since the average particle size of the matrix grains is about 0.5 to 20 μm, a medium-heavy rare earth element near the grain boundary 35 at a depth of about 5 nm from the crystal interface. By concentrating a large amount of 37, the residual magnetic flux density of the permanent magnet 33 can be greatly improved. Further, according to the Nd-Fe-B compound of the present embodiment, the total amount of the medium-heavy rare earth element 37 can be reduced, and the cost of the permanent magnet 33 can be suppressed.

Further, in this embodiment, in order to enhance the demagnetization characteristics described later, La, Ce, Pr, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb are added to the Nd-Fe-B magnet. , Lu, Y, Sc may be included.

The permanent magnet 33 in this embodiment can have a content of medium-heavy rare earth element 37 of 1% by mass or more and 3% by mass or less.

In this embodiment, as the refrigerant, trifluoroiodomethane (CF3I) alone or a mixed refrigerant containing trifluoroiodomethane (CF3I) and another refrigerant is used.

Examples of other refrigerants include CO2, hydrocarbons, ethers, fluoroethers, fluoroalkenes, HFCs, HFOs, HClFOs, HClFOs, HBrFOs and the like. In addition, "HFC" indicates a hydrofluorocarbon. "HFO" is a hydrofluoroolefin composed of a carbon atom, a fluorine atom, and a hydrogen atom, and has at least one carbon-carbon double bond. The "HClFO" consists of carbon, chlorine, fluorine and hydrogen atoms and has at least one carbon-carbon double bond. "HBrFO" consists of carbon, bromine, fluorine and hydrogen atoms and has at least one carbon-carbon double bond.

Examples of HFC include difluoromethane (HFC32), pentafluoroethane (HFC125), 1,1,2,2-tetrafluoroethane (HFC134), 1,1,1,2-tetrafluoroethane (HFC134a), and trifluoroethane. (HFC143a), difluoroethane (HFC152a), 1,1,1,2,3,3,3-heptafluoropropane (HFC227ea), 1,1,1,3,3,3-hexafluoropropane (HFC236fa), 1 , 1,1,3,3-pentafluoropropane (HFC245fa), and 1,1,1,3,3-pentafluorobutane (HFC365mfc) are exemplified.

Examples of fluoroalkenes include fluoroethane, fluoropropene, fluorobutene, chlorofluoroethane, chlorofluoropropene, and chlorofluorobutene. Fluoropropene includes 3,3,3-trifluoropropene (HFO1243zf), 1,3,3,3-tetrafluoropropene (HFO1234ze), 2,3,3,3-tetrafluoropropene (HFO1234yf), and HFO1225. Is exemplified. Examples of fluorobutene include C4H4F4, C4H3F5 (HFO1345), and C4H2F6 (HFO1336). Examples of chlorofluoroethylene include C2F3Cl (CTFE). Examples of chlorofluoropropene include 2-chloro-3,3,3-trifluoro-1-propene (HCFO1233xf) and 1-chloro-3,3,3-trifluoro-1-propene (HCFO1233zd). ..

Trifluoroiodomethane, difluoromethane (HFC32), pentafluoroethane (HFC125), and hexafluoropropene as refrigerants to adjust Global Warming Potential (GWP), vapor pressure, and flame retardant parameters. It is preferable to use one or more of (FO1216). In addition, in order to obtain a vapor pressure that matches the capacity of the equipment, the refrigerant includes HFO1234yf, HFO1234ze, 1,1,1,2-tetrafluoroethane (HFC134a), HFO1123, etc., and affects the vapor pressure and efficiency related to the capacity. It is preferable to adjust the degree of temperature gradient to be applied according to the mixing concentration.

The blending amount of trifluoroiodomethane in the mixed refrigerant is 10% or more and 100% or less, preferably 20% or more and 80% or less, and more preferably 30% or more and 50% or less on a mass basis.

For GWP, the value (100-year value) of the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) is used. Further, as the GWP of the refrigerant not described in AR4, the value of the IPCC Fifth Assessment Report (AR5) may be used, the value described in other publicly known documents may be used, or the known value may be used. Values calculated or measured using the method may be used. According to AR4, the GWP of trifluoroiodomethane is 0.4, the GWP of HFC32 is 675, and the GWP of HFC125 is 3,500.

The GWP of the refrigerant is 750 or less, preferably 500 or less, more preferably 150 or less, still more preferably 100 or less, and particularly preferably 75 or less.

The vapor pressure of the refrigerant at 25 ° C. is preferably in the range of 1.4 MPa to 1.8 MPa. The flame retardancy parameter of the refrigerant represented by the mathematical formula (1) is preferably 0.46 or less.
Fmix = Σi Fi xi ... (1)
Fmix indicates the flame retardancy parameter of the mixed refrigerant, Fi indicates the flame retardancy parameter of each refrigerant component, and xi indicates the mole fraction of each refrigerant component.

As the refrigerating machine oil, a polyol ester oil or a polyvinyl ether oil having a kinematic viscosity at 40 ° C. of 30 to 100 mm2 / s is preferable. The kinematic viscosity is measured based on standards such as ISO (International Organization for Standardization) 3104, ASTM (American Society for Testing and Materials) D445, D7042. The critical melting temperature on the low temperature side of the refrigerant and the refrigerating machine oil is preferably + 10 ° C. or lower.

Examples of the refrigerating machine oil having the above characteristics include polyol ester oil represented by the chemical formulas (1) and (2) and polyvinyl ether oil represented by the chemical formula (3). In the formulas (1) and (2), R1 to R10 represent an alkyl group having 4 to 9 carbon atoms, and may be the same or different from each other. Further, in the formula (3), OR11 is a methyloxy group, an ethyloxy group, a propyloxy group or a butyloxy group, and n is 5 to 15.

As described above, in this embodiment, trifluoroiodomethane (CF3I) alone or a mixed refrigerant containing trifluoroiodomethane (CF3I) and other refrigerants is used as the refrigerant, so that this refrigerant is a closed electric motor. When used in a compressor, the discharge temperature in a closed electric compressor is higher than that in R134a, R410A, R407C, etc., and there is a risk of demagnetizing the permanent magnet used in the electric motor. In the case of rare earth magnets such as neodymium, the temperature change is large, and demagnetization occurs especially on the high temperature side. When the current value of the electric motor that drives the closed electric compressor increases, the discharge temperature of the closed electric compressor also rises, and the demagnetization of the permanent magnet progresses accordingly. In demagnetization, the demagnetization drops sharply from the point where the demagnetization rate exceeds 1%, so it is preferable to control the current value of the electric motor so that the demagnetization rate does not exceed 1%. A means for solving this will be described with reference to FIG.

FIG. 6 is a control circuit diagram of a closed electric compressor according to an embodiment of the present invention. In FIG. 6, the rectifier circuit 62 that takes in the alternating current 61 converts the alternating current into direct current and sends it to the inverter 63. The inverter 63 converts the direct current supplied from the rectifier circuit into an alternating current having a predetermined frequency, and supplies the alternating current to the electric motor 7 of the sealed electric compressor 50. The electric motor 7 drives the compression mechanism 2 to compress the refrigerant. The discharge pipe 22 for discharging the refrigerant of the closed electric compressor 50 is provided with a temperature sensor 64 for detecting the discharge temperature of the discharged refrigerant. The discharge temperature detected by the temperature sensor 64 is transmitted to the inverter control means 66 (control means) via the temperature detection circuit 65.

Further, the control circuit of the closed electric compressor 50 is provided with a current sensor 67 that detects the current supplied from the inverter 63 to the electric motor 7 of the closed electric compressor 50. The current value detected by the current sensor 67 is transmitted to the inverter control means 66 via the current detection circuit.

A storage means 69 is connected to the inverter control means 66. The storage means 69 stores in advance data showing the relationship between the discharge temperature and the current supplied to the electric motor 7. That is, there is a relative relationship between the discharge temperature and the current supplied to the electric motor 7 that the discharge temperature of the closed electric compressor 50 also rises as the current supplied to the electric motor 7 increases. Therefore, since the discharge temperature of the closed electric compressor 50 corresponding to the current value whose demagnetization rate exceeds 1% is naturally determined, the demagnetization rate exceeds 1% by detecting the discharge temperature of the closed electric compressor 50. The current value can be grasped.

In this embodiment, a temperature sensor 64 for detecting the discharge temperature of the refrigerant discharged from the compression mechanism 2 of the closed electric compressor 50 is provided. For example, the temperature sensor 64 is provided on the discharge pipe 22. The discharge temperature of the refrigerant detected by the temperature sensor 64 is transmitted to the inverter control means 66 via the temperature detection circuit 65. In the inverter control means 66, the electric motor in which the demagnetization rate of the permanent magnet exceeds 1% (1% demagnetization start current) or less with reference to the data stored in advance in the storage means 69 and the detected discharge temperature. The current supplied to 7 is controlled. At this time, the current detection circuit 68 detects the current supplied to the electric motor 7 and transmits it to the inverter control means 66. The inverter control means 66 compares the current command value output from the inverter control means 66 to the inverter 63 with the actual current supplied from the inverter 63 to the electric motor 7, and compares the current command value with the detected actual current value. If there is a difference from, make a correction.

According to this embodiment, since the current supplied to the electric motor is controlled based on the signal from the temperature sensor, the temperature of the exhaust gas of the compressor rises due to the use of trifluoroiodomethane. Even in this case, it is possible to control the electric motor to a current that demagnetizes the permanent magnet by 1% or less, and the compressor can be operated stably with high efficiency.

Further, in this embodiment, Nd-Fe-B magnet as a permanent magnet material is used as La, Ce, Pr, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb to enhance demagnetization characteristics. , Lu, Y, Sc. Since it contains any rare earth element, demagnetization due to an increase in temperature can be suppressed.

Further, in this embodiment, the temperature sensor 64 for detecting the discharge temperature of the refrigerant discharged from the compressor is provided, but instead of this, a temperature sensor for detecting the surface temperature of the closed container is used. Is also good.

Further, in this embodiment, the current supplied to the electric motor is controlled, but instead of this, the rotation speed of the electric motor may be controlled.

Next, an example of a refrigeration cycle using the closed electric compressor of this embodiment will be described. FIG. 7 is a cycle configuration diagram of the air conditioner according to the embodiment of the present invention.

In FIG. 7, a high-pressure chamber type closed electric compressor 50 (compressor), an oil separator 72 provided in the discharge circuit 71 of the closed electric compressor 50, and an oil reservoir 9 from the oil separator 72. A four-way switching valve 74 (switching valve) that is connected to the series circuit 73 that returns oil to the air and the discharge circuit 71 of the closed electric compressor 50 to switch the circulation direction of the refrigerant, and a four-way switching valve 74 that is connected to the blower 75. The outdoor heat exchanger 76 attached, the electronic expansion valve 77 for heating connected to the outdoor heat exchanger 76, the receiver 78, and the electronic expansion valve 77 for heating connected via the receiver 78. An electronic expansion valve 79 for cooling, an indoor heat exchanger 81 connected to an electronic expansion valve 79 for cooling and equipped with a blower 80, and a suction pipe 83 of a closed electric compressor 50 are provided in the middle. The accumulator 82 and the suction pipe 83 of the closed electric compressor are sequentially connected by a refrigerant pipe to provide a closed cycle refrigerant circuit. The refrigerant constitutes trifluoroiodomethane (CF3I) and a refrigeration cycle 70 as a mixed refrigerant thereof. A rotor 7a is installed inside the closed electric compressor 50, a permanent magnet 33 is incorporated inside the rotor 7a shown in FIG. 2, and is fixed to the shaft 6 of the closed electric compressor 50 shown in FIG.

According to this embodiment, even if the temperature of the exhaust gas of the compressor rises due to the use of trifluoroiodomethane, the electric motor is controlled to a current that demagnetizes the permanent magnet by 1% or less. It is possible to provide an air conditioner capable of stably operating the compressor with high efficiency.

The sealed electric compressor 50 of the above-described embodiment assumes a scroll type compressor, but the present invention can also be applied to other compressors such as a rotary type, a swing type, and a reciprocating type.

Furthermore, the present invention is not limited to the above-mentioned examples, and includes various modifications. The above-mentioned examples have been described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the described configurations.

1 ... closed container, 2 ... compression mechanism, 3 ... fixed scroll, 4 ... swivel scroll, 5 ... frame, 6 ... shaft, 7 ... electric motor, 7a ... rotor, 7b ... stator, 8 ... lubricating oil, 9 ... Oil reservoir, 11 ... Suction pipe, 12 ... Suction port, 14 ... Discharge port, 22 ... Discharge pipe, 24 ... Coil, 31 ... Magnet housing, 33 ... Permanent magnet, 50 ... Sealed electric compressor, 61 ... AC current , 62 ... rectifier circuit, 63 ... inverter, 64 ... temperature sensor, 65 ... temperature detection circuit, 66 ... inverter control means, 67 ... current sensor, 68 ... current detection circuit, 69 ... storage means, 70 ... refrigeration cycle, 71 ... Discharge circuit, 72 ... Oil separator, 73 ... Series circuit, 74 ... Four-way switching valve, 75 ... Blower, 76 ... Outdoor heat exchanger, 77 ... Electronic expansion valve, 78 ... Receiver, 79 ... Electronic expansion valve, 80 ... Blower, 81 ... Indoor heat exchanger, 82 ... Accumulator, 83 ... Suction pipe

Claims (8)

A high-pressure chamber type closed container, a compression mechanism housed in the closed container for compressing the refrigerant, and an electric motor for driving the compression mechanism are provided.
The electric motor is a compressor including a stator having a coil and a rotor having a permanent magnet.
The refrigerant is trifluoroiodomethane (CF3I) alone or a mixed refrigerant containing the trifluoroiodomethane (CF3I) and another refrigerant.
The material of the permanent magnet is formed by containing a rare earth element in an Nd-Fe-B-based magnet.
The rare earth elements are concentratedly distributed in the vicinity of the grain boundaries of the Nd-Fe-B magnet.
A temperature sensor for detecting the discharge temperature of the refrigerant discharged from the compression mechanism and a control means for controlling the electric motor are provided.
Based on the signal from the temperature sensor, the control means supplies a current to the electric motor so that the current flowing through the electric motor is equal to or less than the 1% demagnetization start current of the permanent magnet at the discharge temperature of the refrigerant. A compressor characterized by controlling the. In claim 1,
The permanent magnet is a neodymium magnet having an intrinsic coercive force of 800 kA / m or more. In claim 1 or 2,
A compressor comprising a temperature sensor for detecting the surface temperature of the closed container in place of the temperature sensor for detecting the discharge temperature . In claim 1 or 2 ,
The control means is a compressor, which controls the rotation speed of the electric motor instead of controlling the current supplied to the electric motor . It is equipped with a high-pressure chamber type airtight container, and is equipped with a compressor that compresses the refrigerant, a switching valve that is connected to the discharge circuit of the compressor and switches the circulation direction of the refrigerant, and is connected to the switching valve and has a blower. An outdoor heat exchanger, an electronic expansion valve for heating connected to the outdoor heat exchanger, an electronic expansion valve for cooling connected to the electronic expansion valve for heating, and an electron for cooling. In an air conditioner equipped with an indoor heat exchanger connected to an expansion valve and equipped with a blower.
The refrigerant is trifluoroiodomethane (CF3I) alone or a mixed refrigerant containing the trifluoroiodomethane (CF3I) and another refrigerant.
The compressor is housed in the closed container and includes a compression mechanism for compressing the refrigerant and an electric motor for driving the compression mechanism.
The electric motor includes a stator having a coil and a rotor having a permanent magnet.
A temperature sensor for detecting the discharge temperature of the refrigerant discharged from the compression mechanism and a control means for controlling the electric motor are provided.
The material of the permanent magnet is formed by containing a rare earth element in an Nd-Fe-B-based magnet.
The rare earth elements are intensively distributed in the vicinity of the grain boundaries of the Nd-Fe-B magnet.
The control means supplies a current to the electric motor based on a signal from the temperature sensor so that the current flowing through the electric motor becomes 1% or less of the demagnetization start current of the permanent magnet at the discharge temperature of the refrigerant. An air conditioner characterized by controlling the. In claim 5,
The permanent magnet is an air conditioner characterized by being a neodymium magnet having an intrinsic coercive force of 800 kA / m or more . In claim 5 or 6,
An air conditioner provided with a temperature sensor for detecting the surface temperature of the closed container in place of the temperature sensor for detecting the discharge temperature . In any one of claims 5 to 7 ,
The control means is an air conditioner characterized by controlling the rotation speed of the electric motor instead of controlling the current supplied to the electric motor .

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