JP2020167746A - Motor and hermetic electric compressor and freezer with the same - Google Patents

Abstract

To provide a motor capable of fixing a permanent magnet without positional deviation while ensuring high productivity, and a hermetic electric compressor and a freezer with the same.SOLUTION: A motor has a positioning part 27 for fitting a permanent magnet 22 on the inner peripheral surface of a back yoke 21 of a rotor 18 and is constructed to fit the permanent magnet 22 on the positioning part 27 to position it. Thereby, the permanent magnet is regulated in its position by the positioning part on the inner peripheral surface of the back yoke and can be fixed at a regular position without positional deviation, and measurement of a fixation position of the magnet and positioning using a jig are not necessary, thus productivity is improved, and the loss of dynamic balance of the rotor caused by positional deviation of the permanent magnet can be prevented to suppress and reduce increase of rotation vibration.SELECTED DRAWING: Figure 3

Description

The present invention relates to an electric motor, a closed electric compressor using the electric motor, and a refrigerating device.

Generally, an electric motor is used in various devices including parts that are driven to rotate, and various devices are used depending on the device used. For example, a freezing device such as a freezer / refrigerator is provided with a closed electric compressor that compresses a refrigerant, and the electric motor is used as a drive source of the closed electric compressor.

With the diversification of foodstuffs, there is a growing demand for larger capacity refrigerators, so the closed electric compressor, which is a rotary drive component for expanding the internal volume of the refrigerator while keeping the external dimensions of the refrigerator, is , Smaller size and lower height are being promoted.

As an electric motor suitable for reducing the size and height of such a closed electric compressor, there is an outer rotor type motor in which a rotor rotates outside the stator (see, for example, Patent Document 1).

FIG. 9 shows a closed electric compressor described in Patent Document 1. In this closed electric compressor, an electric motor element 110 of an outer rotor type motor and a compression element 120 driven by the electric motor element 120 are placed in a closed container 100. It is configured by incorporating it in.

The compression element 120 links the cylinder block 121, the piston 123 reciprocally arranged in the cylinder 122 of the cylinder block 121, and the piston 123 via the connecting rod 124, and reciprocates the piston 123 via the connecting rod 124. It is composed of a crankshaft 125, and the crankshaft 125 is driven by an electric motor element 110.

The electric motor element 110 is composed of a stator 111 and a rotor 112 that rotates around the outer circumference of the stator 111, and is a so-called outer rotor type motor.

The rotor 112 is composed of a tubular back yoke 114 connected to the crankshaft 125 via a flange plate 113, and a plurality of permanent magnets 115 evenly adhered and fixed to the inner peripheral surface of the back yoke 114. ing.

On the other hand, the stator 111 is composed of a core 116 fixed to the bearing portion 126 of the cylinder block 121 and a coil 117 wound around the core 116. Then, a magnetic field is generated by energizing the coil 117 of the stator 111, the back yoke 114 is rotated via the permanent magnet 115, and the piston 123 is reciprocated via the crankshaft 125 integrated with the back yoke 114. , The refrigerant is compressed and used for cooling.

Japanese Unexamined Patent Publication No. 2016-6303

The electric motor element 110 of the sealed electric compressor described in Patent Document 1 is suitable for small size and low profile, but has poor productivity and has a plurality of permanent magnets constituting the rotor 112. There is a problem that the fixed position of the 115 with respect to the inner peripheral surface of the back yoke 114 is easily displaced, and the dynamic balance of the rotor 112 is lost due to the displacement of the magnet position, and the rotational vibration becomes large.

That is, when the plurality of permanent magnets 115 constituting the rotor 112 are fixed to the inner peripheral surface of the back yoke 114, the first permanent magnet is first adhered and fixed, and then the next permanent magnet is used as a reference. Since the magnets are fixed in sequence while measuring the fixing position of the magnets, it takes time to bond and fix the magnets, resulting in poor productivity.

Furthermore, in addition to this, since each permanent magnet that is adhesively fixed in sequence is fixed in sequence while measuring, it is easy for the position to shift from the regular position due to measurement variation, and as a result, the dynamic balance of the rotor 112 is lost and rotational vibration occurs. Was getting bigger.

It has been proposed that the misalignment of each permanent magnet be eliminated by adhering and fixing each permanent magnet while aligning them with a jig. According to this, a jig is required separately and the jig is required. There is a problem that extra time is required for setting and the productivity is further reduced.

The present invention has been made in view of these points, and an object of the present invention is to provide an electric motor capable of surely preventing the displacement of permanent magnets while ensuring high productivity, a closed electric compressor using the electric motor, and a freezing device. It is the one.

In order to achieve the above object, the present invention has a configuration in which a positioning portion for fitting a permanent magnet is provided on the inner peripheral surface of the back yoke, and the permanent magnet is fitted and fixed in the positioning portion.

As a result, the permanent magnet can be fixed in the regular position without being displaced by the positioning part on the inner peripheral surface of the back yoke, and there is no need to measure the fixed position of the magnet or position it with a jig. This can improve productivity, prevent the rotor from losing its dynamic balance due to the displacement of the permanent magnets, suppress rotational vibration, and reduce it.

According to the above configuration, the present invention can provide an inexpensive electric motor with less rotational vibration, a closed electric compressor using the electric motor, and a refrigerating apparatus.

Longitudinal sectional view of a closed electric compressor using an electric motor according to the first embodiment of the present invention. Sectional drawing which shows the electric motor element of the closed type electric compressor according to Embodiment 1. AA sectional view of FIG. 2 showing an electric motor element according to the first embodiment. An enlarged cross-sectional view showing a magnet fixing portion of the back yoke in the electric motor element of the first embodiment. An enlarged cross-sectional view showing a magnet fixing portion of the back yoke in the electric motor element of the second embodiment. An enlarged cross-sectional view showing a magnet fixing portion of the back yoke in the electric motor element of the third embodiment. An enlarged cross-sectional view showing a magnet fixing portion of the back yoke in the electric motor element of the fourth embodiment. Schematic diagram of the refrigerating apparatus according to the fifth embodiment of the present invention. Longitudinal section of a closed electric compressor using a conventional electric motor

The first invention is an outer rotor composed of a stator formed by winding a coil and a rotor formed by fixing a plurality of permanent magnets to the inner peripheral surface of a back yoke that rotates the outer circumference of the stator. The rotor is a type electric motor, and the rotor is provided with a positioning portion for fitting the plurality of permanent magnets on the inner peripheral surface of the back yoke, and the permanent magnets are fitted and fixed in the positioning portion.

As a result, the permanent magnet can be fixed in the regular position without being displaced by the positioning part on the inner peripheral surface of the back yoke, and there is no need to measure the fixed position of the magnet or position it with a jig. In addition to improving productivity, it is possible to prevent the rotor from losing its dynamic balance caused by the displacement of the permanent magnets, suppress rotational vibration, and reduce this.

In the second invention, in particular, in the first invention, the positioning portion is integrally formed on the inner peripheral surface of the back yoke.

As a result, it is not necessary to separately mount a positioning member different from the back yoke on the inner peripheral surface of the back yoke to form a positioning portion, which reduces the material cost of the positioning member and the man-hours for mounting the positioning member. It is possible to further improve productivity, and it is possible to realize the effect of suppressing rotational vibration by preventing the displacement of the permanent magnet at a lower cost.

In the third invention, particularly in the first or second invention, the positioning portion is configured by forming a recess on the inner peripheral surface of the back yoke.

As a result, as in the second inventions, it is possible to prevent the magnetic balance from being lost due to the displacement of the permanent magnets while ensuring higher productivity, and to suppress and reduce the rotational vibration.

The fourth invention, in particular, in the first or second invention, is that the positioning portion is provided with a protrusion on either the inner peripheral surface of the back yoke or the outer peripheral surface of the permanent magnet, and the other is a recess that fits into the protrusion. Is provided and configured.

As a result, it is possible to suppress the decrease in the plate thickness of the back yoke caused by providing the positioning portion, and the adverse effect caused by providing the positioning portion, that is, the magnetic flux generated by providing the positioning portion and reducing the plate thickness of the back yoke. It is possible to suppress a decrease in rotational performance due to a decrease in the density saturation level. Therefore, it is possible to suppress rotational vibration by preventing the displacement of the permanent magnet while suppressing deterioration of rotational performance. That is, it is possible to both prevent deterioration of rotational performance and suppress rotational vibration.

A fifth aspect of the present invention, particularly in the first or second invention, is such that the positioning portion is formed by projecting a convex portion on the inner peripheral surface of the back yoke that abuts on both end edges of each permanent magnet to regulate the position. is there.

As a result, the reduction in the back yoke plate thickness caused by the provision of the position regulating portion can be eliminated, and the rotational vibration is suppressed by preventing the permanent magnet from being displaced while suppressing the deterioration of the rotational performance due to the decrease in the magnetic flux density saturation level. Can be realized. That is, it is possible to realize both prevention of deterioration of rotational performance and suppression of rotational vibration at a higher level than that of the fourth invention, and it is possible to obtain a high-performance and low-vibration electric motor.

The sixth invention, in particular, in the first or second invention, has a cross-sectional shape such that the back yoke plate thickness of the central portion thereof is thicker than the back yoke plate thickness of both end portions. ..

As a result, even if the plate thickness of the back yoke is thin at both ends of the positioning portion, the plate thickness of the central portion is thick, so that the magnetic flux density saturation level of the magnetic flux formed in the back yoke is substantially the same as when the positioning portion is not provided. It is possible to suppress the rotational vibration by preventing the displacement of the permanent magnet while suppressing the deterioration of the rotational performance. That is, it is possible to realize both prevention of deterioration of rotational performance and suppression of rotational vibration at a higher level than that of the fourth invention, and it is possible to obtain a high-performance and low-vibration electric motor.

A seventh invention is a closed-type electric compressor using the electric motors of the respective inventions. The closed-type electric compressor comprises a compression element and an electric motor element for driving the compression element, and the electric motor element is the first. It is composed of an electric motor according to any one of the first to sixth inventions.

As a result, due to the high productivity and rotational vibration suppressing effect of the electric motors of the first to sixth inventions, it is possible to obtain an inexpensive and less vibrating sealed electric compressor.

The eighth invention is a refrigerating device using the sealed electric compressor, and the refrigerating device has a refrigerant circuit in which a compressor, a radiator, a depressurizing device, and a heat absorber are connected in a ring shape by a pipe, and the compression is performed. The machine is a closed electric compressor of the seventh invention.

As a result, it is possible to obtain a refrigerating device that is inexpensive and has less vibration noise due to the effect of the closed electric compressor.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to this embodiment.

(Embodiment 1)
FIG. 1 is a vertical sectional view of a closed electric compressor using an electric motor according to the first embodiment of the present invention, FIG. 2 is a sectional view showing an electric motor element of the closed electric compressor according to the first embodiment, and FIG. 2A is a cross-sectional view taken along the line AA of the first embodiment, and FIG. 4 is an enlarged cross-sectional view showing a magnet fixing portion of the back yoke in the motor element of the first embodiment.

In FIGS. 1 to 4, the closed electric compressor according to the first embodiment includes an electric motor element 2 driven by an inverter power supply (not shown) in a closed container 1 formed by drawing and molding an iron plate. A compression element 3 driven by the electric motor element 2 is housed in each, and oil 4 is stored in the bottom of the closed container 1. Further, in the closed container 1, for example, a refrigerant gas 5 such as a hydrocarbon-based R600a having a low global warming potential is at a pressure equivalent to that of the low pressure side of a refrigerating apparatus (not shown) at a relatively low temperature. It is enclosed.

The electric motor element 2 and the compression element 3 are integrally assembled to form a compressor main body 6, and the compressor main body 6 is elastically supported in the closed container 1 by a coil spring 7.

The compression element 3 is mainly composed of a cylinder block 8, and a cylindrical cylinder 9 is formed in the cylinder block 8 and a piston 10 is reciprocally fitted therein. A valve plate 11 is attached to the open end of the cylinder 9 to form a compression chamber 12. Further, the cylinder head 13 is fixed so as to cover the valve plate 11 and cover it.

A main bearing portion 14 is formed in the lower portion of the cylinder block 8, and the crankshaft 15 serving as a rotation shaft is pivotally supported.

The crankshaft 15 is composed of a spindle portion 15a pivotally supported by the spindle portion 14 and an eccentric shaft portion 15c formed via a brim portion 15b, and the eccentric shaft portion 15c is formed from the lower end of the spindle portion 15a. It is provided with a refueling passage 16 that communicates with the upper end of the. Further, the lower end of the spindle portion 15a is immersed in the oil 4 stored in the closed container 1, and the upper end of the eccentric shaft portion 15c is opened to the upper part in the closed container 1. The eccentric shaft portion 15c is connected to the piston 10 via a connecting rod 17.

The electric motor element 2 includes a rotor 18 and a stator 19, and the rotor 18 rotates outside the stator 19 to form an inverter-driven outer rotor type motor suitable for miniaturization and thinning.

The rotor 18 includes a disk-shaped flange plate 20 fixed to the spindle portion 15a, a ring-shaped back yoke 21 fixed to the end of the flange plate 20 by welding or the like, and an inner circumference of the back yoke 21. It is composed of a plurality of permanent magnets 22 fixed in close contact with the surface. In this embodiment, the permanent magnet 22 is adhesively fixed to the inner peripheral surface of the back yoke 21 by an adhesive 23, but the present invention is not limited to this, and for example, it may be fixed by double-sided tape or the like. It may be fixed by using various fixing means.

On the other hand, the stator 19 is composed of a core 24 and a coil 25 wound around the core 24. The stator 19 is arranged so as to be surrounded by a permanent magnet 22 of the rotor 18 so as to be coaxial with the rotor 18 while ensuring an insulating distance between the coil 25 and the cylinder block 8. It is fixed to the lower side of the cylinder block 8 by a fixing bolt 26.

Here, as shown in FIGS. 3 and 4, the rotor 18 has the same number of positioning portions 27 as the permanent magnets 22 formed on the inner peripheral surface of the back yoke 21. In this example, upper and lower strip-shaped recesses 28 are integrally formed on the inner surface of the back yoke 21 by cutting to form a positioning portion 27.

Then, each permanent magnet 22 is fitted into the positioning portion 27, and is adhesively fixed to the positioning portion 27 with an adhesive 23. Adhesive 23 is used for fixing the permanent magnet 22 to the positioning portion 27 in this embodiment, but the present invention is not limited to this, and for example, it may be fixed with double-sided tape or the like, and an appropriate fixing means. It may be fixed using.

The operation and operation of the sealed compressor configured as described above will be described below.

First, the operation as a closed electric compressor will be briefly explained. When the electric motor element 2 is energized from an inverter power supply (not shown), a current flows through the stator 19, a magnetic field is generated, and the rotor 18 fixed to the spindle portion 15a of the crankshaft 15 rotates.

By the rotation of the rotor 18, the piston 10 reciprocates in the compression chamber 12 via the connecting rod 17 rotatably attached to the eccentric shaft portion 15c of the crankshaft 15, and the compression element 3 performs a predetermined compression operation. Do.

Next, the positioning effect of the permanent magnet 22 on the rotor 18, which is a feature of the present invention, will be described.

As described above, when the positions of the permanent magnets 22 fixed to the inner peripheral surface of the back yoke 21 of the rotor 18 are displaced, the dynamic balance is lost and the vibration becomes large. However, the rotor 18 of the electric motor element 2 has the back yoke. Since the positioning portion 27 is provided on the inner peripheral surface of the 21, the permanent magnet 22 can be accurately positioned and fixed at a regular position by fitting each permanent magnet 22 into each of the positioning portions 27.

Therefore, when fixing the permanent magnet 22 to the back yoke 21 as in the conventional case, the permanent magnet 22 is attached to the back yoke 21 without measuring the fixed position or using a jig and without shifting the position. It can be fixed to the inner peripheral surface.

As a result, the working time required for fixing the permanent magnet 22 to the back yoke 21 can be significantly shortened, and the productivity is greatly improved. Moreover, since the permanent magnet 22 can be fixed without being displaced, the dynamic balance of the rotor 18 is not disturbed, and it is possible to suppress an increase in rotational vibration.

Further, in the present embodiment, since the positioning portion 27 is integrally formed by cutting a recess 28 on the inner peripheral surface of the back yoke 21, a positioning member different from the back yoke 21 is separately provided. It is not necessary to mount the positioning portion on the inner peripheral surface of the back yoke, and the material cost of the positioning member and the man-hours for mounting the positioning member can be reduced to further improve the productivity. Therefore, it is possible to suppress the rotational vibration by preventing the permanent magnet 22 from being displaced at a lower cost.

Further, the closed electric compressor using the electric motor element 2 should be an inexpensive and low vibration closed electric compressor because the electric motor element 2 can be provided at a low cost and its rotational vibration is suppressed. Can be done.

In particular, in this embodiment, the electric motor element 2 is driven by an inverter, but since the rotor 18 of the electric motor element 2 does not lose its dynamic balance, it has good followability to changes in the number of revolutions, and the dynamic balance is lost. If this is the case, the rotational vibration of the rotor 18 can be suppressed even if the inverter control is performed, which tends to increase the rotational vibration, which is effective.

(Embodiment 2)
FIG. 5 is an enlarged cross-sectional view showing a magnet fixing portion of the back yoke in the electric motor element according to the second embodiment of the present invention.

In this embodiment, the positioning portion 27 is provided to suppress the rotational vibration while suppressing the plate thickness reduction of the back yoke 21 caused by the positioning portion 27.

That is, the positioning portion 27 of the second embodiment has a configuration in which two protrusions 30 are provided on the outer peripheral surface of the permanent magnet 22 and a recess 31 into which the protrusions 30 are fitted is provided on the inner peripheral surface of the back yoke 21. In the present embodiment, the protrusion 30 is provided on the permanent magnet 22 and the recess 31 is provided on the back yoke 21, but the reverse may be true.

According to this configuration, the decrease in the plate thickness of the back yoke 21 can be made extremely small, and the decrease in rotational performance due to the decrease in the magnetic flux density saturation level caused by the decrease in the plate thickness of the back yoke 21 is effective. It can be suppressed, and the effect of suppressing rotational vibration by preventing misalignment can be realized while suppressing deterioration of rotational performance.

More specifically, in the configuration shown in the first embodiment, the thickness of the back yoke 21 is reduced by providing the positioning portion 27. As a result, the magnetic flux generated in the back yoke 21 is saturated in a small state, in other words, the magnetic flux density saturation level is lowered, and the rotational performance is lowered, such as the rotational torque is lowered.

However, according to the configuration of the second embodiment, the positioning portion 27 has a protrusion 30 and a recess 3.
Since it is formed of 1, the decrease in the plate thickness of the back yoke 21 can be made extremely small.

Therefore, it is possible to reduce the decrease in the magnetic flux density saturation level caused by the provision of the positioning unit 27 and suppress the decrease in the rotational performance, and to realize the effect of suppressing the rotational vibration while suppressing the decrease in the rotational performance. Can be done.

(Embodiment 3)
FIG. 6 is an enlarged cross-sectional view showing a magnet fixing portion of the back yoke in the electric motor element according to the third embodiment of the present invention.

In this embodiment, the effect of suppressing the rotational vibration by providing the positioning portion 27 while suppressing the decrease in the plate thickness of the back yoke 21 caused by the provision of the positioning portion 27 is further enhanced.

That is, the positioning portion 27 according to the third embodiment has a convex portion 33 protruding from the inner peripheral surface of the back yoke 21 so as to abut on both end edges of the permanent magnets 22 to regulate the position.

According to this configuration, since the convex portion 33 is formed so as to protrude without reducing the plate thickness of the back yoke 21, the reduction of the back yoke plate thickness caused by providing the positioning portion 27 can be eliminated.

Therefore, the decrease in rotational performance due to the decrease in the magnetic flux density saturation level of the back yoke 21 can be eliminated, and the effect of suppressing the rotational vibration by preventing the decrease in the magnetic flux density saturation level and the displacement of the permanent magnet 22 can be achieved. It can be compatible at a higher level than the invention. Therefore, it is possible to obtain an electric motor with lower vibration and higher performance.

(Embodiment 4)
FIG. 7 is an enlarged cross-sectional view showing a magnet fixing portion of the back yoke in the electric motor element according to the fourth embodiment of the present invention.

Also in this embodiment, the effect of suppressing the rotational vibration by providing the positioning portion 27 while suppressing the decrease in the plate thickness of the back yoke 21 caused by the provision of the positioning portion 27 is enhanced.

That is, the positioning portion 27 has a curved cross-sectional shape so that the back yoke plate thickness T1 at the center thereof is thicker than the back yoke plate thickness T2 at both ends.

As a result, even if the plate thickness T2 of the back yoke 21 is thin at both ends of the positioning portion 27, the plate thickness T1 of the central portion is thick, so that the magnetic flux density saturation level of the magnetic flux formed in the back yoke 21 is the positioning portion 27. The level can be set to the same level as in the case where the magnet 22 is not provided, and the rotational vibration can be reduced by preventing the permanent magnet 22 from being displaced while suppressing the deterioration of the rotational performance.

(Embodiment 5)
FIG. 8 is a schematic view showing the configuration of a refrigerating device using the closed compressor according to any one of the first to fourth embodiments of the present invention. Here, the refrigerant circuit is equipped with the sealed electric compressor described in any one of the first to fourth embodiments, and the outline of the basic configuration of the refrigerating apparatus will be described.

In FIG. 8, the refrigerating apparatus stores a heat-insulating main body 35 that opens on one side and opens and closes the opening with a door, and a partition wall 38 that divides the inside of the main body 35 into a storage space 36 for articles and a machine room 37. A refrigerant circuit 39 for cooling the inside of the space 36 is provided.

The refrigerant circuit 39 has a configuration in which the sealed compressor described in the first or second embodiment as the compressor 40, the radiator 41, the decompression device 42, and the heat absorber 43 are connected and connected in an annular shape by a pipe 44. ing. The heat absorber 43 is arranged in a storage space 36 provided with a blower (not shown). As shown by the arrow M in FIG. 8, the cooling heat of the heat absorber 43 is agitated so as to circulate in the storage space 36 by the blower, and the inside of the storage space 36 is cooled.

Since the closed compressor is inexpensive and has less vibration, the refrigerating apparatus described above can be an inexpensive refrigerating apparatus with less vibration noise. Since the total height of the closed compressor is kept low, the height of the machine room 37 of the refrigerating device can be kept low and the volume of the storage space 36 can be increased.

Although the present invention has been described above using the above-described embodiment, the configuration described in the above-described embodiment is shown as an example of carrying out the present invention, and varies within the range of achieving the object of the present invention. Needless to say, it includes an outer rotor type electric motor, a closed type compressor, and a refrigerating device to which the configuration based on the technical idea of the present invention is applied.

As described above, the present invention can be an inexpensive electric motor with less rotational vibration, a closed electric compressor using the electric motor, and a freezing device, and can be used as a freezer / refrigerator, an air conditioner, a commercial showcase, or vending. It can be widely applied to various refrigerating devices such as machines.

2 Motor element 3 Compressor element 18 Rotor 19 Stator 21 Back yoke 22 Permanent magnet 23 Adhesive 25 Coil 27 Positioning part 28 Concave 30 Protrusion 31 Recess 33 Convex 39 Refrigerant circuit 40 Compressor 41 Radiator 42 Decompression device 43 Heat absorption Instrument T1 Back yoke plate thickness at the center T2 Back yoke plate thickness at both ends

Claims (8)

An outer rotor type electric motor consisting of a stator configured by winding a coil and a rotor configured by fixing a plurality of permanent magnets to the inner peripheral surface of a back yoke that rotates the outer circumference of the stator. The rotor is an electric motor in which a positioning portion for fitting the plurality of permanent magnets is provided on the inner peripheral surface of the back yoke, and the permanent magnets are fitted and fixed in the positioning portion. The electric motor according to claim 1, wherein the positioning portion is integrally formed on the inner peripheral surface of the back yoke. The electric motor according to claim 1 or 2, wherein the positioning portion is formed by forming a recess on the inner peripheral surface of the back yoke. The electric motor according to claim 1 or 2, wherein the positioning portion is provided with a protrusion on either the inner peripheral surface of the back yoke or the outer peripheral surface of the permanent magnet, and the other is provided with a recess for fitting into the protrusion. The electric motor according to claim 1 or 2, wherein the positioning portion is formed by projecting a convex portion that contacts both end edges of each permanent magnet and regulates the position on the inner peripheral surface of the back yoke. The electric motor according to claim 1 or 2, wherein the positioning portion has a cross-sectional shape in which the back yoke plate thickness of the central portion thereof is thicker than the back yoke plate thickness of both end portions. A sealed electric compressor comprising a compression element and an electric motor element for driving the compression element, wherein the electric motor element is composed of the electric motor according to any one of claims 1 to 6. A freezing device having a refrigerant circuit in which a compressor, a radiator, a decompressing device, and a heat absorber are connected in a ring shape by a pipe, and the compressor is a closed type compressor according to claim 7.

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